Belief that we are unaware of a great deal that is in our minds is pervasive. But many people believe that Sigmund Freud, the dominant popularize of psychology in the 20th century, “invented” or “discovered” the unconscious. Freud, however, drew on a long tradition of philosophy and research in this field, and this paper briefly surveys some of these earlier thinkers, as well as glancing at Freudian thought and concepts of the unconscious in post-Freudian psychology.
That we are unaware of aspects of our mentality or consciousness is not a new idea. Plato’s theory of reminiscence, for example, holds that all knowledge already resides within each person and learning is the process of bringing this innate knowledge into conscious awareness. The root of “education,” educare, reflects the idea of “leading out” knowledge already unconsciously held within the pupil. In a different way, the four humors were an unconscious physiological influence on mentality. Many Classical and Medieval thinkers believed that the predominance of one of four basic fluids in a person’s body determined whether people were cold- or hot-tempered, melancholy or optimistic. Thus, mental outlooks were determined by substances outside conscious control. This classification formed the basis for much medical and dietary theory and practice, as well as a shorthand of psychological explanation
The modern concept of the unconscious arose in the 17th and 18th centuries, though of course people had noticed earlier that not all action is motivated by conscious thought. Montaigne, for example, wrote in 1590 that
We do not command our hair to stand on end and our skin to quiver with desire or with fear; the hand often goes where we do not send it; the tongue becomes tied and the voice choked at their own time; the appetite for food and drink, even when, having nothing to cook, we would gladly forbid it, does not fail to stir up those parts that are subject to it, neither more nor less than this other appetite, and it abandons us as unseasonably, whenever it pleases.
In the seventeen-century, however, thinkers were reacting strongly against Scholasticism, the authority-centered school of thought that had been dominant in Europe for several centuries. René Descartes (1596–1650) was among the most prominent of this new breed of natural philosopher. In considering the human psyche, he held that people were dual: a mechanistic animal body made of physical substance which was joined with an incorporeal mind responsible for thought, language, and spiritual life and made of an altogether different type of substance. The animal aspect which ran a person’s bodily processes was not unconscious; rather, it had no consciousness at all. Descartes viewed all non-human terrestrial life as mere automata, with no mind, feelings, or soul, incapable of feeling pain anymore than a machine does. Thus, mentally, humans are rational beings whose minds are conscious and whose non-mental aspects are non-conscious. He did not posit an unconscious aspect of the mind; rather, there was a consciousness/mind and a physical automaton with an unbridgeable gulf between them. His dualistic theories were important in stimulating later thinkers and researchers.  Descartes also held that knowledge is what can be clearly defined, that is, it must be rational and able to be expresses in language. Paul Bishop maintains that
the modernity of Descartes lay in his promotion of consciousness to a position of supremacy, in effect identifying the soul and consciousness. This step is extremely significant … for if consciousness (cogitatio) constitutes the essence or the nature of the soul (essentia sive natura animae), then all of those rich and various psychic functions attributed to the soul become correspondingly downgraded, ignored, or repressed. No longer the “divine spark” within the individual human being, the ego – the subject of the cogito – becomes a mere mathematical point, and consciousness is no longer an object in itself, but that for which something else is an object.
How two completely dissimilar substances, mental and physical, could interact and influence each other – as mind and body clearly do – was a problem from the start. Descartes proposed that the pineal gland was the place where mental substance interacted with the body. Later Moses Mendelssohn (1729-1786) proposed the theory that there was an interchange between the mind/soul and the body, an influential explanation some of whose proponents “argued that the passions of the soul produce corresponding passions in the body…” This strain of thought developed into Vitalism and later influenced the German philosopher Schiller.
Another early viewpoint was that of philosopher John Locke (1632-1704) and his fellow empiricists, who held that the human mind was completely empty at birth (a tabula rasa or “blank slate”), and that it is formed exclusively by experience, that is, by sense impressions that register in the consciousness. The first mention of unconscious mentality may well be in G. W. Leibniz’s critique of this theory written in 1704. A German philosopher and mathematician, contemporary of Newton and co-inventor of the calculus, Leibniz (1646-1716) objected that consciousness was not identical with mental activity, and that the mind was full of insensible or imperceptible perceptions. These last were perceptions that people do not notice (either because they are too slight, too many, not sufficiently able to be distinguished or because attention is focused elsewhere) but which in certain circumstances could be recalled to awareness:
we let them pass without reflection and even without being noticed; but if some one calls our attention to them immediately afterwards and makes us notice, for example, some noise which was just heard, we remember it and are conscious of having had at the time some feeling of it. Thus they were perceptions of which we were not immediately conscious. …
These insensible perceptions indicate and constitute the identity of the individual, who is characterized by the traces or expressions which they preserve of the preceding states of this individual, in making the connection to his present state; and these can be known by a superior mind, even if this individual himself should not be aware of them, that is to say, when a definite recollection of them will no longer be in him. But they (these perceptions, I say) furnish the means of recovering this recollection at need, by the periodic developments which may some day happen.
He concludes that “insensible perceptions are of as great value in pneumatology [psychology] as insensible corpuscles are in physics and it is equally as unreasonable to reject the one as the other under the pretext that they are beyond the reach of our senses.” For Leibniz unlike Locke, scholar Nicholas Rand states, “consciousness or the feeling of self certainly proves personal identity but in no way constitutes it.” Not surprisingly, Leibniz also disagreed with Descartes’ idea that knowledge is limited to what is clearly defined or articulated. In 1714 he wrote:
Each soul knows the infinite, knows everything, but confusedly. Just as when I am walking along the shore of the sea and hear the great noise it makes, though I hear the separate sounds of each wave of which the total sound is made up, I do not discriminate them one from another; so our confused perceptions are the result of the impressions which the whole universe makes on us.
In the 18th and early 19th centuries, this area of natural philosophy became of great interest to many thinkers and researchers. Several built on Leibniz’ ideas, though his New Essays were not published until 1765. His main student, Christian Wolff (1679-1754), introduced an empirical element which drew on English thinkers Francis Bacon (1561-1626) and Thomas Hobbes (1588-1679), who Locke and his school also followed. One of Wolff’s students, Ernst Platner (1744-1818), coined the term Unconscious (Unbewußtsein) in 1776.
According to Nicholas Rand, the first essay to deal exclusively with unconscious mental phenomena was written in 1759 by Swiss aesthetician Johann Georg Sulzer (1720-1779), entitled: “Explanation of a Paradoxical Psychological Proposition: That We Sometimes Act Not Only Without Motive or A Visible Cause, But Even Against Compelling Motives and Despite Fully Convincing Reasons.” Sulzer expanded Leibniz’ distinction between clear and obscure perceptions and ideas, arguing that all actions may have an unconscious aspect. In fact, the more obscure a feeling or memory, the more powerful it is. Rand brings out the similarities of Sulzer’s thought with that of British empiricist and skeptic David Hume (1711-1776), who wrote in his Treatise of Human Nature (1739) about the associative nature of the mind, which moves from one thought to the next almost automatically. As Rand says:
This fundamental associative disposition of the mind is an extraordinary facility of transition, even a magical faculty, sustained by resemblance, continguity, and the relation of cause and effect among ideas. Hume went on to examine the role of habitually associated ideas or mental customs in the formation of belief. He described the latter, especially judgments of cause and effect, as nearly always arising immediately, without the mind being aware of performing any such operation. In fact, the association of ideas in belief “may operate on our mind in such an insensible manner as never to be taken notice of, and may even in some measure be unknown to us” (103). The production of belief in the mind occurs by a “secret operation and without once being thought of” (144). The mind makes its habit-driven transitions from one idea to the next so quickly that there is no time for reflection.
Maine de Biran (1766-1824), who came out of the French empirical school to become an intellectualist and finally a mystical theosophist, also built on Leibniz’s ideas. In an 1807 lecture “On Obscure Perceptions,” he renamed imperceptible perceptions “affective impressions,” since if such stimuli were not perceived they could not logically be called perceptions.
A strictly scientific investigation of the unconscious developed between about 1810 and 1875 in Britain in the psychophysiological school. It wished to pin down the relationship between mind and brain and between intellectual and physical activity. Up until this time bodily movement, particularly in animals, was thought to derive from spirit or soul, Aristotle holding that “the soul enables animals to move, by releasing pneuma (or spirit) which runs through the body. … It was God who permitted animals to move, by equipping them not only with the means, but also the will to do so.” When Luigi Galvani produced motion in a frog’s leg by stimulating it with electricity, this action implied that the body’s motion might be mechanical, and the term reflex was coined. A new breed of researchers began by assuming the mind-body dualism of Descartes, which held that the body was an automaton that could function without any intervention of the mind. Their neurological research centered on reflexes and the ability of nerves to excite muscles to action automatically, without action on part of the brain. At first the brain was viewed as the only organ of consciousness. However, this dualism was challenged by the discovery of the voluntary and autonomous nervous systems which both included the brain. Many concluded that volition was an illsion; as Thomas Henry Huxley wrote in 1874:
The feeling we call volition is not the cause of the voluntary act, but simply the symbol in consciousness of the stage of the brain which is the immediate cause of the act. Like the steam whistle which signals but doesn’t cause the starting of the locomotive.
This type of neurophysiological research into consciousness and the brain continues strong into the present.
Certain states of consciousness were fertile areas for researchers into unconscious mentality. Maine de Biran introduced the idea of repression, and distinguished in his work as a whole between sensations that create mental representations or ideas (perceptions) and sensations from either external or internal sources that affect mind or body but fail to create such representations (affective impressions). These last are unconscious. As Biran says in relation to sleep, dreams and somnambulism, but also with application to intoxication, hallucinations, etc.:
If we could still be surprised by the phenomena that habit has rendered utterly familiar to us, we would surely feel astonishment and fright on thinking about the prodigious difference between these two alternating modes of existence: one in which we live, feel, and act with the consciousness and inner feeling of our existence, of our impressions, and our acts: whereas in the other, we live, feel and act, often enough with the aid of the selfsame organs and apparently in the same way, yet without consciousness, without ego, without memory, and remaining like strangers, in one of these modes of existence, to everything that we have experienced, felt, imagined or done in the other.
One of Platner’s students, German Romantic poet and literary critic Jean-Paul Richter (1763-1825), explored the unconscious in regard to dreams and creative imagination, writing:
We regard the rich expanse of the ego all too narrowly when we leave out the enormous realm of the unconscious, this genuine inner Africa. Within the entire wide globe of memory, hardly a few illuminated mountaintops revolve at any one time in the mind; the rest of the world remains shrouded in their shadow. Were we completely conscious of ourselves, we would be our own creators and infinite. [Yet there is] something dark that is not our creation but instead our creator.
In trying to explain creativity and artistic imagination, thinkers from the late 1700 through the Romantic period turned more and more to the unconscious mind. This was a departure from earlier ideas:
In The Mirror and the Lamp (1953) M. H. Abrams traced the gradual emergence of the idea of a spontaneous and instinctive verbal art that both modifies the external objects of perception and expresses the inner recesses of the poet’s mind. In addition, the Platonic conception of enthusiasm or dictation by a supernatural visitant slowly mutated into the theory of the hidden power of the mind itself, a power rising from within in sudden, effortless, and unanticipated bursts.
This approach is seen in an example of creative unconscious mental action given by Sulzer:
At times thoughts will not develop or let themselves be clearly grasped while we pay full attention to them. Yet long afterwards they will appear, of their own accord, in the greatest clarity just when we are not in search of them, so that it seems as though in the interim they has grown unnoticed, like a plant, and now suddenly stand before us in their full development and bloom. Many a conception ripens gradually within us until, freeing itself from the mass of obscure ideas, it suddenly emerges into the light.
The interplay between the conscious and the unconscious was disputed. While Wilhem Joseph Schelling (1775-1854) held that consciousness is subordinated to the unconscious in artistic creation, Schiller argued that “unconsciousness combined with reflection constitutes the poetic artists,” so that there was a balance between these two aspects of mentality.
In the mid-1860s Scottish author and critic E. S. Dallas explored the source in human psychology of the pleasure taken in poetry, concluding that, as expressions of the unconscious or hidden aspect of consciousness, poetry evoked these hidden aspects of the reader. Rand maintains that Dallas “is the first writer to give center stage to the unconscious in a comprehensive theory of artistic creation, expression, and reception. Among his many ideas, that of hidden pleasure – the spectator’s resonance with the secrecy embodied in art – is of intrinsic interest.” Dallas held that “We enjoy poetry and art because they appeal to our own hidden selves. Through suggestion and allusion, they let us glimpse the unceasing traffic between the conscious and unconscious realms of the soul.” In Britain the proponents of this view that creativity was not connected to the conscious will or mind included such figures as Wordsworth, Coleridge, Shelley, Hazlitt, and De Quincy, so that by 1900 the position that creativity and imagination lay in the unconscious was very widely accepted.
Another altered state heavily involved in psychopathological research and speculation centered on hypnotism. This practice has its roots in the animal magnetism of Austrian physician Anton Mesmer (1734-1815). In his dissertation for his medical degree, he proposed a scientific explanation of the effect of the gravitation of celestial bodies on the human body. He argued that gravity was caused by an all-embracing cosmic fluid which also caused magnetism, electricity, heat, and light. Its action in the body he at first called animal (that is, belonging to animate or breathing beings) gravitation and later animal magnetism. He claimed that this magnetism could be controlled by the application of magnets in cases of hysteria and other psychosomatic illnesses. In this process the animal magnetism or fluid was transmitted from Mesmer to the patient or groups of patients, often in a rather theatrical setting. His demonstrations before the Viennese and Parisian medical establishment were met with skepticism, the latter body declaring that the cures were due to the imagination of the patients.
Mesmer’s work was continued by the Marquis de Puységur (1751-1825), a French aristocrat who experimented extensively with animal magnetism and its therapeutic uses, emphasizing trancelike states which he called magnetic sleep and later artificial somnambulism. On awakening from these states patients often could not remember what had happened while they were entranced and were subject to suggestion, obeying instructions unawares after they had left the trance state. They also seemed in that state to be more knowledgeable in certain respects:
For example, several individuals were able to diagnose their own problems and recommend treatments. This begged certain questions. Was artificial somnambulism allowing patients to recover information that had simply been forgotten? Or was there some vast, submerged library in the mind that could be consulted during sleep? Needless to say, the early romantic philosophers become particularly interested in Puységur’s work, being inclined to believe that his patients were obtaining information from the world soul – the universal unconscious. Artificial somnambulism was quickly perceived as a possible short cut to the numinous.
By the time of Puységur’s death most Mesmerists were employing his methods rather than Mesmer’s.
One of the first scientifically respectable research into hypnotic phenomena was made by Scottish surgeon James Braid (1795-1860), who coined the term “hypnotism” (from Greek hypnos, sleep). He pioneered hypnotherapy, sometimes used alone but more often in conjunction with ordinary medical treatments. Rather than being a form of sleep, as he first supposed, he came to believe that it was a physiological state caused by prolonged, intensive concentration on some object, related to such practices as meditation. In several papers he compared it to the states attained through yoga and other oriental practices:
Inasmuch as patients can throw themselves into the nervous sleep, and manifest all the usual phenomena of Mesmerism, through their own unaided efforts, as I have so repeatedly proved by causing them to maintain a steady fixed gaze at any point, concentrating their whole mental energies on the idea of the object looked at; or that the same may arise by the patient looking at the point of his own finger, or as the Magi of Persia and Yogi of India have practised for the last 2,400 years, for religious purposes, throwing themselves into their ecstatic trances by each maintaining a steady fixed gaze at the tip of his own nose; it is obvious that there is no need for an exoteric influence to produce the phenomena of Mesmerism. … The great object in all these processes is to induce a habit of abstraction or concentration of attention, in which the subject is entirely absorbed with one idea, or train of ideas, whilst he is unconscious of, or indifferently conscious to, every other object, purpose, or action.
Braid thus felt that hypnosis was a condition brought about by patients concentrating their attention for a prolonged period on some object, rather than something imposed on or induced in them by the practitioner, and that it could be a useful adjunct in treating certain medical conditions.
Hypnotism received more widespread attention when it was championed by the influential French neurologist and professor of anatomical pathology, Jean-Martin Charcot (1825-1893). Practitioners from Mesmer forward had used hypnotism to treat hysteria and other psychosomatic illnesses which were not taken seriously by the medical establishment. Charcot believed hysteria was a neurological disease, present in both men and women, with the susceptibility for hypnosis as a predisposing symptom. He distinguished hysterical, paralytic and other conditions as having either organic or neurological causes, and used hypnotism to treat the latter with some success. Charcot profoundly influenced Freud, who attended his lectures while he was in Paris in 1885-6. This contact was a large factor in turning Freud’s interest from neurology to psychopathology. Though Charcot was very influential in his own lifetime, his psychiatric ideas were not widely or long accepted, and hysteria was in time considered to be an artifact of suggestion.
Physician and philosopher Pierre Janet (1859-1947) did a great deal of psychological research beginning in 1882. He discovered that the personality could be split, which he called “dissociation,” the suggestibility of patients under hypnosis, the ability of subconscious traumas and ideas to cause disease, the therapeutic value of automatic writing and other means of reaching the unconscious mind, and a means to replace these dysfunctional unconscious ideas and so end the behavioral and physiological symptoms. He coined the term “subconscious” in an attempt to differentiate the scientific usage for the part of the mind responsible for psychological illness from that of philosophers which was still heavily influenced by the Romantic school. (p. 45, Hidden Minds). Janet, however, differed from the later psychoanalytic school in his estimation of the importance and role of the unconscious, holding that:
It is equally dangerous always to locate in the subconscious of the patient exciting reminiscences, no trace of which appears in his consciousness. To my notion, one should distrust the subconscious. … In the works of the spiritualists and occultists the subconscious has become a marvelous principle of knowledge and action far beyond our poor thought; for the psychoanalyst it has become the principle of all neuroses, the dues ex machina to which one appeals to explain everything. It does not seem to me that the subconscious merits such honor and I think that some precaution is needed to keep it in its place. A psychic phenomenon, which is always in reality a certain mode of conduct in the patient should always be verifiable by the observer.
As Frank Tallis remarks: “Janet’s work … was outstanding. He invented what we would now recognize as psychotherapy and linked his treatments to a specific model of psychopathology (i.e. a model of how symptoms develop). Central to his model was what he called the subconscious. Without retrieving and modifying subconscious material, hysterical symptoms would persist.” (Hidden Minds, pp. 50-1) Freud was aware of Janet’s discoveries, which predated his first publication on the subject in 1893 but which he later utilized in his psychoanalytic school without giving Janet credit: “From the very beginning Freud was well aware of Janet’s priority. But posterity was at stake. Subsequently, whenever Freud had the opportunity, he would describe misleading and distorted versions of Janet’s ideas in his own works. He was tireless in his personal attacks on Janet, and even accused him of antisemitism.” (ibid., p. 52)
Two bedrocks of psychoanalysis or “talk therapy,” catharsis and free association, were developed by earlier thinkers. In his 1857 interpretation of Aristotle’s concept of catharsis, philologist and philosopher Jacob Bernays (1824-1881) opposed the standard interpretation of a “purification of the passions or their transformation into virtue.” Rather, he proposed that “catharsis designates a type of treatment for oppressed persons that does not seek to transform or suppress the element oppressing them, but rather to arouse and drive it into the open, thereby bringing about relief.” He cited Porphyry’s view that feelings only become stronger when repressed, whereas “if these affects are elicited in brief utterance and in the right proportion, they will induce joy in moderation; the affections will be stilled, discharged, and calmed in a good-mannered way and without any violence. . . . [Bernays] thus validated the existence in ancient times of a psycho-medical theory that sees curative effect in the verbal or mimetic calling-forth of hitherto suppressed, stifled, or inhibited emotions.”
Free association was investigated extensively by English scientist Francis Galton (1822-1911) in the 1870s, though his work was largely unnoticed. He found through self-study that associated ideas “lay bare the foundations of a man’s thoughts with curious distinctness and exhibit his mental anatomy with more vividness and truth than he would probably care to publish to the world.” In the 1880s German physician and founder of academic psychology Wilhem Wundt (1832-1920) experimented extensively with association and this work was widely noticed. His work was later modified by a group of psychiatrists, Carl Jung, Franz Beda Riklin, and Eugen Bleuler, who developed from it the concept of “complexes.” Thus, the major concepts of talk therapy, free association and catharsis, were widely discussed in intellectual circles decades before Freud began his work.
Today’s popular ideas about the unconscious or subconscious derive from the widespread acceptance, indeed dominance, of the psychology and therapy of psychoanalysis in the first three-fourths of the 20th century. This influence remains even when Freud and his psychoanalytic method have been largely discredited. Though Freud is popularly credited with the discovery or invention of the concept of the unconscious, as we’ve seen, many ideas about the unconscious had been formulated and researched before Freud. He incorporated many of these into his theories, often giving them a “twist” to fit in with his own particular views. This was true of concepts such as repression, dissociation, suggestion, free association, and catharsis through verbalization.
In his analysis of the streams of German philosophical thought that Freud drew upon in developing his concept of the unconscious, Günther Gödde writes that he distinguishes “three main historic-philosophical tradition-lines of the unconscious …” Investigating all these thinkers in any detail is beyond the scope of this article, except to summarize some of Gödde’s general points. “The first of these is the tradition-line of the cognitive unconscious, which stems from the era of the Enlightenment.” This includes such figures as Leibniz, Johann Friedrich Herbart (1776-1814), Gustav Theodor Fechner (1801-1887), Hermann von Helmholtz (1821-1894), and Theodor Lipps (1851-1914). Herbart introduced the concept of the “law of the threshold,” which states that “certain mental contents are repressed below the threshold of consciousness but can return into consciousness,” an idea that “remains today a feature of the highly differentiated psychology of cognition.” Before his own theories were formulated, Freud studied the work of Theodor Lipps, a leading German academic psychologist, and in 1898 wrote to his mentor, Wilhem Fliess (1858-1928), that he
found the substance of my insights stated quite clearly in Lipps, perhaps rather more so than I would like. “The seeker often finds more than he wished to find!” Consciousness is only a sense organ; all psychic content is only a representation; all psychic processes are unconscious. The correspondence [of our ideas] is close in details as well; perhaps the bifurcation from which my own new ideas can branch off will come later.
Gödde explains that a “second (Romantic) tradition-line arose from the fear that the Enlightenment would stagnate into a flat and lifeless rationalism if the emotional, natural, biological, fantastic, and irrational dimensions of human experience were not taken into account.” It grew out of the works of Johann Georg Hamann (1730-1888), Johann Gottfried Herder (1744-1803), and Johann Wolfgang von Goethe (1749-1832), and peaked in the natural and medical philosophies of the early and middle 19th century. Herder believed that an unconsciously but collectively developed ability, language, was the driving force behind human development and progress and held also that the unconscious became embodied through such activities as art, culture, and language. Thus, as Andrew Bowie explains,
given how much we unreflectively assimilate from the cultures into which we are socialized, what we think and feel must be based on something which does not all come to the level of reflective evaluation while it is being acquired. This symbolic and other expressive material can subsequently become rigidified and abstract, losing its power when subjected to reflection, and so creating the need for something which can replace it.
The romantic line of thought also expressed itself in both the Sturm und Drang (Storm and Stress) and German Classicist literary movements, Goethe moving from one to the other in the course of his life. As Paul Bishop writes:
The decisive factor that links both the Storm and Stress and German classicism to the unconscious and, in turn, to Freud is also … a central theme in Goethe’s Faust: the relationship between time and pleasure. Both Goethe and Freud were aware that pleasure is fleeting and transient, and both recognized that one of the deepest human desires is to secure and retain pleasure at all costs, in spite of time and decay. The view that this desire to sustain pleasure over time is often unconscious and irrational, the idea that such desire should be channeled and redirected in useful and socially acceptable ways, and the notion that the ontological basis of this unconscious desire inheres in a materialist, yet non-reductionist, understanding of nature, constitute a central features of the Storm and Stress and German Classicism that persist, sometimes in a subterranean or unacknowledged form, in the work of Freud.
Freud was also attracted to Goethe’s non-reductive materialism and Stoic-Epicurean principles.
The third tradition-line mentioned by Gödde
developed in opposition to the two main streams of post-Kantian German idealism, on the one hand, the idealistic philosophy of reason associated with Johann Gottlief Fichte (1762-1814) and Georg Wilhelm Friedrich Hegel (1770-1831), and on the other hand, Schelling’s philosophy of nature … This tradition-line emerged from Schelling’s redefinition of the will as impulse (Drang), drive (Trief), and desire (Begierde), and led to the recognition of potentially dangerous and destructive urges within human nature. One can speak, in this context, of the “drive-related irrational” … tradition-line of the unconscious. This tradition-line includes Arthur Schopenhauer’s metaphysics of the will to life …, Eduard von Hartmann’s metaphysics of the unconscious …, and Friedrich Nietzsche’s anti-metaphysical notion of the “will to power...”
The German idealists sought to unite mind with nature. According to Andrew Bowie, the work of Wilhelm Joseph Schelling (1775-1854) in relation to the unconscious remains relevant to modern discussions. The schools that rose out of his thought “primarily invoked the unconscious in order to refer to the ‘dark sides’ of the nature and the soul.” Like his contemporaries interested in medicine, psychology, and natural philosophy, Freud was exposed to all these lines of thought, beginning in the 1870s while he was in secondary school, university, and medical school.
Although Freud began as a neurophysiologist, he became interested in psychopathology. In 1883 an older colleague and pioneer in the use of the unconscious in psychological treatment, Josef Breuer, told Freud of his experiences with his patient Bertha Pappenheim (Anna O), who he treated with memory substitution under hypnosis, the method also developed by Janet. This case intrigued Freud who in 1885 went to Paris to study under Charcot, one of the most prominent neurophysiologists as well as a great promoter of hypnosis in treating hysteria. When Freud returned to Vienna in 1886 he married and set up a private practice treating nervous diseases, working together with Breuer. Together in 1893 they published “On the Psychical Mechanism of Hysterical Phenomena: Preliminary Communication,” a short paper that became the first chapter of Studies in Hysteria (1895). The two authors soon parted company as Freud’s theories centered more and more strongly around sexuality as the driving force in human psychology.
In this same year Freud wrote his Project for a Scientific Psychology, an ambitious proposal “to furnish a psychology that shall be a natural science: that is, to represent psychical processes as quantitatively determinate states of specifiable material particles, thus making those processes perspicuous and free from contradiction.” He had to abandon the project because the investigative technology was insufficient to carry it out, even as it remains insufficient today to approach this goal. At that time little was understood about the functioning of neurons or the brain, beyond cell theory and reflexes, and so Freud’s suggestions were speculative and have often proved to be incorrect. He viewed the nervous system as reflexive, and the brain and neurons as passively dissipating forces that came either from the environment or from instincts and drives.
In Freud’s simple reflex model conflict arose when somatic instincts raised the energy level … of the nervous system and this energy could not be discharged through motoric activity because of social conventions or family sanctions. This high level of energy in the psychic system… was perceived as pain (unpleasure) by the conscious sensing system and the energy (and the consequent unpleasure) remained until discharged. Of particular importance was that the “executive” aspect of the nervous system (the Ego) derived its energy from internal instinctual sources and so was subject to contamination and corruption arising from the instinctual drives. A final feature of Freud’s nervous system was the absence of inhibitory neurons. Perhaps because Freud conceived of neurons [as] transmitters and receivers of instinctual energy (something like a power network) rather than as signal transducers and transformers, he had difficulty conceiving of inhibition of neuronal activity; in his model once instinctual energy was introduced into the brain it remained forever until discharged. In order to divert this energy from immediate discharge Freud proposed that the ego used what he termed “inhibiting side cathexes,” a process bearing no relationship to modern neurophysiological concepts of inhibition …. It is of interest that the familiar psychoanalytic terms “inhibiting ego,” cathexis (meaning charging of a neuron with energy), repression, ego, primary and secondary process thinking, and hallucinatory wish-fulfillment are all present in the neural model of the Project.
His views on neurophysiology thus informed many of his psychoanalytic concepts and interpretations. His Project was not published until 1966, being hailed by some critics as the highpoint of Freud’s aspirations, by others as presenting neurophysiological ideas that were already too psychologized. Be that as it may, in 1897 Freud entered into a period of intense self-psychoanalysis, finding that “The interpretation of dreams is in fact the royal road to a knowledge of the unconscious; it is the securest foundation of psychoanalysis.” From his self-observation and work with patients he published The Interpretation of Dreams in 1900, and although not immediately popular it became very influential.
Freud’s psychoanalytic theory rested on the existence and dynamic role of the unconscious mind. He divided human mental activity into three levels: the conscious that is in awareness, the preconscious which can be brought into awareness, and unconscious which is outside awareness. Because unconscious content influenced behavior and psychological states, he called it the dynamic unconscious. As he wrote in 1923:
The division of the psychical into what is conscious and what is unconscious is the fundamental premise of psychoanalysis; and it alone makes it possible for psychoanalysis to understand the pathological processes in mental life … and to find a place for them in the framework of science….
… we have arrived at the term or concept of the unconscious … by considering certain experiences in which mental dynamics play a part. We have found – that is, we have been obliged to assume – that very powerful mental processes or ideas exist … which can produce all of the effects in mental life that ordinary ideas do …, though they themselves do not become conscious…. [P]sychoanalytic theory … asserts that the reason why such ideas cannot become conscious is that a certain force opposes them, that otherwise they could become conscious, and that it would then be apparent how little they differ from other elements which are admittedly psychical.
The contents of the unconscious were pictured as largely identical to that of the conscious mind – feelings, thoughts, memories, perceptions – only they were disassociated from language and so unable to be accessed consciously. To explain this, he posited a repression mechanism that strips the verbal element from the content of the mind:
What we could permissibly call the conscious idea of the object can now be split up into the idea of the word (verbal idea) and the idea of the thing (concrete idea) … It strikes us all at once that now we know what is the difference between a conscious and an unconscious idea. The two are not, as we supposed, different records of the same content situate in different parts of the mind, nor yet different functional states of cathexis in the same part; but the conscious idea comprises the concrete idea plus the verbal idea corresponding to it, whilst the unconscious idea is that of the thing alone…. Now too, we are in a position to state precisely what it is that repression denies to the rejected idea in the transference neuroses – namely, translation of the idea into words which are to remain attached to the object. The idea which is not put into words or the mental act which has not received hyper-cathexis then remains in the unconscious in a state of repression.
Psychoanalysis was the means of reuniting these influential unconscious elements with language so they could be dealt with consciously and thus lose their hold over the patient. For Freud the most important energy in the human psychobiology was sexual, which he termed libido. Later he proposed a structure for the unconscious mind, consisting of id, ego, and superego, and the interaction of these structures explained most psychological phenomena. As early as 1917 Freud maintained that his conception of the dominating influence of the unconscious in human life had dealt the third and most devastating blow to human narcissism, the other two blows being the heliocentric system which removed the earth from the center of the universe and Darwin’s theory of evolution which rejected humanity’s traditional status as separate from the animal kingdom, a special creation that stood above the rest of nature.
Freud's rise from obscurity was rapid. In 1902, at the suggestion of a Viennese physician, Freud and four other physicians inaugurated the Wednesday Psychological Society, which slowly grew in attendance so that by 1906 there were 18 members. In 1908 they changed the name to the Viennese Psychoanalytic Society, and then,
In an extraordinarily short period of time, Freud rose from relative obscurity – the chairman of a local psychology club – to international celebrity. By the 1920s the image of Sigmund Freud, an elderly man with a beard and an intense, slightly troubled expression, had become synonymous with the mind and its mysteries. Even those with little or no knowledge of academic psychology could claim some familiarity with Freud’s ideas and method.
As the vocabulary and principles of psychoanalysis spread through Europe and North America, so it was that the unconscious became established as a fundamental feature of mental life – relevant to everyday behavior and experience. A model of mind, in which the unconscious influenced judgement, slips of the tongue, and the content of dreams, gradually insinuated itself in the collective imagination.
. . . .
By the 1950s and 1960s psychoanalysis had scored a remarkable cultural victory. . . . Freud had become a colossus – ranking in stature with the world’s greatest thinkers….
. . . Thus, as America became the dominant world culture – so it was that Frued’s ideas were propagated far and wide. The degree of integration . . . works at the level of numerous implicit assumptions made about the mind and human behavior – sexual desire is profoundly important; all actions can ultimately be explained; secrets can be buried in the mind; and so on.
The other psychoanalytic psychologist whose ideas on the unconscious remain influential is Carl Jung. A protégé of Freud after their meeting in 1907, he had already developed his own ideas about the unconscious, drawing on Vitalist sources. Although chosen by Freud as his successor, Jung soon went his own way after disagreeing on several major points, particularly that psychology is driven almost exclusively by sexual drives and infant sexual experiences. In 1912 Jung underwent a mental crisis and in response for several years underwent concentrated self-analysis, undergoing vivid visions, travelling to other worlds and encountering mythical and biblical characters, stating later that “The years when I was pursuing my inner images were the most important in my life – in them everything essential was decided. It all began then; the later details are only supplements and clarifications of the material that burst forth from the unconscious, and at first swamped me. It was the prima materia for a liftetime’s work.”
In Jung’s analytical psychoanalysis he proposed three levels of awareness: the conscious, the personal unconscious, and the collective unconscious. The collective unconscious contained the symbolic and mythic elements common to humankind:
Jung states that the primordial images of the collective unconscious are inherited, but by this he does not mean that a person has consciously appropriated the images that his ancestors had, but rather than he shares with his ancestors the same predispositions for experiencing the world. For example, basic fears of the dark or of snakes or of monstrous shapes are not learned but acquired through heredity. As these typical situations are repeated again and again, archetypes – the contents of the collective unconscious – are produced and manifest themselves in the forms of myths and symbols.
In Jung’s system, the patient attempts to restore equilibrium by balancing the various subpersonalities within themselves.
The psychoanalytic schools became dominant in Europea and especially in America, its concepts appearing in literature, drama, movies, journalism, popular culture and academic criticism. Although this school had had its critics all along, beginning in the 1960s its hegemony was strongly challenged by cognitive scientists, neurobiologists, feminists, and others who criticized psychoanalysis as unscientific, speculative, unfalsifiable, biased, inaccurate, and ineffective. Examination of Freud’s methods for arriving at his psychoanalytic theories revealed them to be flawed and at times even intellectually dishonest, and today this form of therapy is in the minority, for economic as well as scientific and cultural reasons. Two recent psychotherapy debacles, memories of childhood abuse retrieved under hypnosis and the epidemic of multiple personality disorder, were spearheaded by psychologists associated with the Freudian school. Nonetheless, the unconscious has, if anything, become more dominant in recent psychological and brain research.
The disrepute into which Freud and psychoanalysis have fallen has not dampened research into the unconscious. On the contrary, the emphasis on neuropsychological and cognitive research have further emphasized its importance in human life. This paper can only examine a few of the exciting findings and areas of research of the past few decades.
One area of particular interest, dating back several centuries, was how the brain and mind are related. Scientists are still nowhere near accomplishing the goals of Freud’s Project for a Scientific Psychology, despite technological advances that have led to tremendously greater knowledge of the physiological mechanics that accompany psychological processes and more intensive psychological testing.
The development of computers during and after World War II had important implications for psychological research. As Frank Tallis points out:
For thousands of years contemporary technology has been recruited to help explain the mind. In many respects the history of psychology has been shaped by the selection of metaphors. Wax tablets, clocks, looms, pipes and valves, engines, hydraulic systems, telegraphs, and the telephone exchange have all been employed to represent the mind and mental processes. From ancient times to the middle of the twentieth century the mind was transformed from a marionette (neuron is Greek for ‘string’) to an electrical maze; however, [Alan] Turning gave psychology the ultimate metaphor. It was so good, in only a few decades psychologists and neuroscientists were not saying that the brain was like a computer, they were saying that the brain was a computer.
The post-war period saw the beginning of the cognitive school of psychology, which “seeks to explain human perception and cognition in terms of computational processes” by taking information processing and computers as their model. The brain is pictured as consisting of many separate processors, working independently or connected in various ways. At first such researchers were apt to deny the importance or even existence of unconscious mental activity because it was strongly associated with psychoanalysis and romanticism. The significant body of research from the 1940sand 1950s into subliminal perception was largely ignored once the cognitive model took hold until Norman Dixon published Subliminal Perception: The Nature of a Controversy in 1971. There he examined carefully the evidence for this phenomenon, and cognitive psychologists began to acknowledge that much of the brain’s functions were preconscious and unconscious. They reasoned that
If the mind functions like a computer, then it very probably processes information in a serial fashion. Perception must involve many tiers of processing, not all of which are accessible to consciousness. Indeed, only the final stages of processing might produce an event in awareness (for example, perception of a word display). Thus a stimulus exposed for a very brief period of time might be processed sufficiently to merit an adjustment in perception threshold, but insufficiently to enter awareness.
That much of mental activity takes place before or without awareness was no new idea. As early as 1913 researchers had observed that in seemingly conscious acts, physiological processes preceded conscious awareness: “We can be conscious of our acts only through the sensory processes set up after the act has begun.” This disconnect between neural actions and thoughts about them have been confirmed in detail, as researcher Marcel Kinsbourne points out:
Freud’s emphasis on the Unconscious, to the detriment of the Conscious, now seems even more well founded than he knew. Awareness of an external change lags several hundred milliseconds behind the stimulus onset, and substantially behind the cortical processing that establishes the nature and significance of the external change. Moreover, by the time the individual, that is, the brain, is conscious of the input, decisions for corresponding action, if any, have already been made. Again, some hundreds of milliseconds elapse before the brain is aware of the decision-making already in progress. Our brains, these self-organizing, self-stabilizing adaptive devices, both analyze the situation and select adaptive action before they (i.e., we) are aware of any of this.
The consequence of this fact for cognitive researchers is that “Once we realize that the business of the brain is essentially conducted preconsciously, we can be more open to the idea that what is conscious is substantially predetermined and biased unconsciously.” (ibid.) And such researchers have concluded that:
most of a person’s everyday life is determined not by their conscious intentions and deliberate choices but by mental processes that are put into motion by features of the environment and that operate outside of conscious awareness and guidance. 
For this reason,
the cognitive unconscious is very different from the dynamic [psychoanalytic] unconscious…: rather than being a powerful unitary system, it is fragmented across a large number of informationally encapsulated and narrowly focused specialist computational mechanisms; it is not populated with personal-level mental entities such as beliefs, desires, and memories, but subpersonal mental representations that carry information relevant only for highly circumscribed perceptual and cognitive tasks; and its representations are inaccessible to consciousness by virtue of architectural constraints rather than the operation of a repressive force.
Some psychologists object to the cognitive model of the mind as an oversimplification. Jerome Kroll defends a psychoanalytic approach, saying:
The essential argument here seems to be the ongoing attempt to explain the messiness of human motivation and behavior in terms of neural mechanisms and, more recently, computer and information processing models. The enterprise is laudable, but the sticking point always seems to be the problem in moving from biological process to meaning and semantics…. Psychodynamic explanations may be wrong (however defined) in detail or even in large part, but psychodynamic theory engages thought, emotion, and action at the symbolic and personal level, and until a process explanation can make that leap to the world of worry, desire, and affection, it will fall short in its attempts to render psychodynamics superfluous. – J. Kroll (2002)
The relationship Freud claimed between consciousness and language also remains controversial. Freud, like Descartes, held that language was central to consciousness. Dream analysis and talk therapy were effective because they brought repressed unconscious material into verbal expression, and thus removed it from the unconscious. Confining consciousness to contents that can be put into language does not seem reasonable to other investigators. In medical school, for example, Antonio Damasio would ask what produces consciousness.
Curiously, I always got the same answer; language did it. I was told that creatures without language were limited to their uncognizant existence but not we fortunate humans because language made us know … The answer sounded too easy, far too simple for something which I then imagined unconquerably complex, and also quite implausible, given what I saw when I went to the zoo.
J. Melvin Woody expands on the objections to tying consciousness to language:
To make consciousness dependent upon language entails a drastic simplification of the stream of thought that automatically consigns much of the complexity and subtle richness of experience to the domain of the unconscious. This is especially true of the life of feeling, where our verbal resources seem especially inadequate and we most often find ourselves at a loss for words. We have far richer language for distinguishing the varieties of mosses and moths than the subtleties of human emotions. Indeed, [William] James complains that classical empiricism dissolved the connective tissue and musculature of experience into a mosaic of simple ideas or impressions because it failed to recognize the existence of feelings of tendency and relation and the vague halo or fringe that surrounds and accompanies every moment of experience, “the dying echo of whence it came to us, the dawning sense of whither it is to lead.” James warns that if we attend only to the things we can name, we will end by invoking occult intellectual processes to supply the connections we have thereby ignored, but which were nonetheless present in experience all along.
A key debate on the unconscious has reflected a deeper philosophical argument; in approaching the mind, should explanations follow the format of the laws of natural science or is it necessary to couch understanding in terms typically employed in the humanities? Advances in cognitive-affective neuroscience arguably provide a new basis for incorporating both perspectives; the structure of the brain-mind allows the embodiment of both conscious and unconscious mental processes. Such advances have already influenced clinical practice, but their full impact remains to be determined.
One of the authors of the above expands his thoughts further:
Subjective consciousness exists, and it would be a tragedy indeed if science were to exclude it once more from the natural order of things, simply because the manner in which the perceptual apparatus is constructed (and the scientific technology that has flowed from the manner of its construction) makes it easier for us to study the mind as an object in the external world than as the interior of a living subject.
That the danger of excluding subjectivity from neuroscience indeed exists is reflected in Oliver Sacks’ memorable comment (in 1984) to the effect that “neuropsychology is admirable, but it excludes the psyche.” He elaborated:
“Neuropsychology, like classical neurology, aims to be entirely objective, and its great power, its advances, come from just this. But a living creature, and especially a human being, is first and last … a subject, not an object. It is precisely the subject, the living ‘I,’ which is excluded.”
As even very basic functioning of the human brain continues to be revealed in unexpected findings such as mirror neurons and the roles of the glia cells, we may expect many new explanations and surprises in scientists’ researches into the human conscious and unconscious.
 An excellent survey of the development of this idea is in “The Hidden Soul: The Growth of the Unconscious in Philosophy, Psychology, Medicine, and Literature, 1750-1900” by Nicholas T. Rand, in American Imago, 61:3, Fall 2004, pp. 257-89.
 In “The Power of the Imagination,” quoted in “The Hidden Soul,” pp. 274-5.
 The foregoing discussion based on “The Hidden Soul,” pp. 282.
 Paul Bishop, “Unconscious from Storm and Stress to Weimar classicism” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, pp. 31-2.
 Paul Bishop, “Unconscious from Storm and Stress to Weimar classicism” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, p. 34.
 In New Essays Concerning Understanding, written in 1704 but not published until 1765; quoted in “The Hidden Soul” pp. 261, 266-7.
 Rand, “The Hidden Soul,” p. 266.
 Paul Bishop, “Unconscious from Storm and Stress to Weimar classicism” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, p. 33.
 “The Hidden Soul,” p. 276; quoting the 1978 Oxford edition of Hume.
 Hidden Minds: A History of the Unconscious, Frank Tallis, 2002, p. 31.
 Quoted in Hidden Minds: A History of the Unconscious, Frank Tallis, 2002, p. 32.
 From “New Considerations on Sleep, Dreams, and Somnambulism “ (1809), quoted in “The Hidden Soul,” p. 269.
 Jean-Paul Richter in School for Aesthetics (1804), quoted in “The Hidden Soul,” p. 258.
 “The Hidden Soul,” p. 284.
 Quoted in “The Hidden Soul,” p. 284.
 Correspondence between Schiller and Goethe 2:372; quoted in Paul Bishop, “Unconscious from Storm and Stress to Weimar classicism” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, p. 37.
 Rand, “The Hidden Soul,” p. 285.
 Hidden Minds: A History of the Unconscious, Frank Tallis, 2002, p. 21.
 "The Power of the Mind over the Body: An Experimental Inquiry into the nature and acuse of the Phenomena attributed by Baron Reichenbach and others to a 'New Imponderable - Hypnosis explained',", The Edinburgh Medical and Surgical Journal, vol. 66, 1846, pp. 286-311; quoted on Wikipedia, “The history of hypnosis,” http://en.wikipedia.org/wiki/History_of_hypnosis.
 Kelly, p. 51.
 Principles, p. 272; quoted in Psychology of the Unconscious by William L. Kelly, 1991, p. 40.
 “The Hidden Soul,” p. 280. Bernays was the uncle of Freud’s wife.
 “The Hidden Soul,” p. 281.
 Günther Gödde, “Freud and nineteenth-century philosophical sources on the unconscious” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, pp. 262. The following discussion will rely on his work unless otherwise indicated.
 Freud to Fliess, August 31, 1898; quoted in Gödde, p. 274.
 Günther Gödde, “Freud and nineteenth-century philosophical sources on the unconscious” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, pp. 263.
 Paul Bishop, “Unconscious from Storm and Stress to Weimar classicism” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, pp. 37-8.
 Andrew Bowie, “The Philosophical Significance of Schelling’s Conception” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, p 62.
 Paul Bishop, “Unconscious from Storm and Stress to Weimar classicism” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, p. 30.
 Paul Bishop, “Unconscious from Storm and Stress to Weimar classicism” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, pp. 48, 53.
 Günther Gödde, “Freud and nineteenth-century philosophical sources on the unconscious” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, pp. 263.
 Andrew Bowie, “The Philosophical Significance of Schelling’s Conception” in Thinking the Unconscious, ed. Angus Nicholls and Martin Liebscher, Cambridge University Press, 2010, p 58.
 Project for a Scientific Psychology, 1895/1966, p. 295; quoted in Neuroscience of the Mind on the Centennial of Freud’s Project for a Scientific Psychology, ed. Bilder and LeFever, 1998, p. xi.
 “Dreams: Disguise of Forbidden Wishes or Transparent Reflections of a Distinct Brain State?”, Robert W. McCarley, in Neuroscience of the Mind on the Centennial of Freud’s Project for a Scientific Psychology, ed. Bilder and LeFever, 1998, pp.118-9.
 Freud, “The Ego and the Id,” 1923, quoted in “Dispensing With the Dynamic Unconscious,” Gerard O’Brien and Jon Jureidini, Philosophy, Psychiatry, & Psychology, 9:2, June 2002, p. 142.
 “the Unconscious, “ S. Freud, 1915; quoted in “Dispensing With the Dynamic Conscious,” J. Melvin Woody, Philosophy, Psychiatry, & Psychology, 9:2, June 2002, p.155.
 In Introductory Lectures on Psychoanalysis; see Hidden Minds: A History of the Unconscious, Frank Tallis, 2002, ch. 10.
 Hidden Minds: A History of the Unconscious, Frank Tallis, 2002, pp. 73-4, 90.
 Quoted in Minds: A History of the Unconscious, Frank Tallis, 2002, p. 77.
 Kelly, 1991, p. 115.
 Hidden Minds: A History of the Unconscious, Frank Tallis, 2002, p. 92.
 “The Last Rites of the Dynamic Unconscious,” Gerard O’Brien and Jon Jureidini, Philosophy, Psychiatry, & Psychology, 9:2, June 2002, p.163.
 Hidden Minds: A History of the Unconscious, Frank Tallis, 2002, p. 95.
 Marcel Kinsbourne, “Taking the Project Seriously: The Unconscious in Neuroscience Perspective” in Bilder and LeFever, p. 112.
 “The Unbearable Automaticity of Being,” J. A. Bargh and T. L. Chartrand, American Psychologist 54:462-79 (1999); quoted in “varieties of Social Cognition,” E. L. Uhlmann, D. A. Pizarro, P. Bloom, Journal for the Theory of Social Behaviour 38:3 (2008), p. 293.
 “Dispensing With the Dynamic Unconscious,” Gerard O’Brien and Jon Jureidini, Philosophy, Psychiatry, & Psychology, 9:2, June 2002, p. 146.
 “The Nine Lives of the Dynamic Unconscious,” Jerome Kroll, , Psychiatry, & Psychology, 9:2, June 2002, p.160.
 The Feeling of What Happens, A. Damasio, 1999, p. 107; quoted in “Dispensing With the Dynamic Conscious,” J. Melvin Woody, Philosophy, Psychiatry, & Psychology, 9:2, June 2002, p.156.
 “Dispensing With the Dynamic Conscious,” J. Melvin Woody, Philosophy, Psychiatry, & Psychology, 9:2, June 2002, p.156.
 “The Cognitive-Affective Neuroscience of the Unconscious, “ Dan J. Stein, Mark SOlms, and Jack van Honk, CNS Spectrums 11:8, August 2006, p. 582.
 Mark Solms, “Before and after Freud’s Project” in Neuroscience of the Mind on the Centennial of Freud’s Project for a Scientific Psychology, ed. Bilder and LeFever, 1998, p. 9.