Probably none of my empirical Concepts has met with so much misunderstanding as the idea of the collective unconscious. In what follows I shall try to give (1) a definition of the concept, (2) a description of what it means for psychology, (3) an explanation of the method of proof, and (4) an example.
The collective unconscious is a part of the psyche which can be negatively distinguished from a personal unconscious by the fact that it does not, like the latter, owe its existence to personal experience and consequently is not a personal acquisition. While the personal unconscious is made up essentially of contents which have at one time been conscious but which have disappeared from consciousness through having been forgotten or repressed, the contents of the collective unconscious have never been in consciousness, and therefore have never been individually acquired, but owe their existence exclusively to heredity. Whereas the personal unconscious consists for the most part of complexes) the content of the collective unconscious is made up essentially of archetypes.
The concept of the archetype, which is an indispensable correlate of the idea of the collective unconscious, indicates the existence of definite forms in the psyche which seem to be present always and everywhere. Mythological research calls them "motifs"; in the psychology of primitives they correspond to Lévy-Bruhl's concept of "representations collectives," and in the field of comparative religion they have been defined by
Hubert and Mauss as "categories of the imagination" Adolf Bastian long ago called them "elementary" or "primordial thoughts." From these references it should be clear enough that my idea of the archetype-literally a pre-existent form-does not stand alone but is something that is recognized and named in other fields of knowledge.
My thesis, then, is as follows: In addition to our immediate consciousness, which is of a thoroughly personal nature and which we believe to be the only empirical psyche (even if we tack on the personal unconscious as an appendix), there exists a second psychic system of a collective, universal, and impersonal nature which is identical in all individuals. This collective unconscious does not develop individually but is inherited. It consists of pre-existent forms, the archetypes, which can only become conscious secondarily and which give definite form to certain psychic contents.
Medical psychology, growing as it did out of professional practice, insists on the personal nature of the psyche. By this I mean the views of Freud and Adler. It is a psychology of the person, and its aetiological or causal factors are regarded almost wholly as personal in nature. Nonetheless, even this psychology is based on certain general biological factors, for instance on the sexual instinct or on the urge for self-assertion, which are by no means merely personal peculiarities. It is forced to do this because it lays claim to being an explanatory science. Neither of these views would deny the existence of a priori instincts common to man and animals alike, or that they have a significant influence on personal psychology. Yet instincts are impersonal, universally distributed, hereditary factors of a dynamic or motivating character, which very often fail so completely to reach consciousness that modern psychotherapy is faced with the task of helping the patient to become conscious of them. Moreover, the instincts are not vague and indefinite by nature, but are specifically formed motive forces which, long before there is any consciousness, and in spite of any degree of consciousness later on, pursue their inherent goals. Consequently they form very close analogies to the archetypes, so close, in fact, that there is good reason for supposing that the archetypes are the unconscious images of the instincts themselves, in other words, that they are patterns of instinctual behaviour.
The hypothesis of the collective unconscious is, therefore, no more daring than to assume there are instincts. One admits readily that human activity is influenced to a high degree by instincts, quite apart from the rational motivations of the conscious mind. So if the assertion is made that our imagination, perception, and thinking are likewise influenced by inborn and universally present formal elements, it seems to me that a normally functioning intelligence can discover in this idea just as much or just as little mysticism as in the theory of instincts. Although this reproach of mysticism has frequently been levelled at my concept, I must emphasize yet again that the concept of the collective unconscious is neither a speculative nor a philosophical but an empirical matter. The question is simply this: are there or are there not unconscious, universal forms of this kind? If they exist, then there is a region of the psyche which one can call the collective unconscious. It is true that the diagnosis of the collective unconscious is not always an easy task It is not sufficient to point out the often obviously archetypal nature of unconscious products, for these can just as well be derived from acquisitions through language and education. Cryptomnesia should also be ruled out, which it is almost impossible to do in certain cases. In spite of all these difficulties, there remain enough individual instances showing the autochthonous revival of mythological motifs to put the matter beyond any reasonable doubt. But if such an unconscious exists at all, psychological explanation must take account of it and submit certain alleged personal aetiologies to sharper criticism.
What I mean can perhaps best be made clear by a concrete example You have probably read Freud's discussion  of a certain picture by Leonardo da Vinci: St. Anne with the Virgin Mary and the Christ-child. Freud interprets this remarkable picture in terms of the fact that Leonardo himself had two mothers. This causality is personal. We shall not linger over the fact that this picture is far from unique, nor over the minor inaccuracy that St, Anne happens to be the grandmother of Christ and not, as required by Freud's interpretation, the mother, but shall simply point out that interwoven with the apparently personal psychology there is an impersonal motif well known to us from other fields. This is the motif of the dual mother) an archetype to be found in many variants in the field of mythology and comparative religion and forming the basis of numerous "reprsentations collectives." I might mention, for instance, the motif of the dual descent, that is, descent from human and divine parents, as in the case of Heracles, who received immortality through being unwittingly adopted by Hera. What was a myth in Greece was actually a ritual in Egypt: Pharaoh was both human and divine by nature. In the birth chambers of the Egyptian temples Pharaoh's second, divine conception and birth is depicted on the walls; he is "twice-born." It is an idea that underlies all rebirth mysteries, Christianity included. Christ himself is "twice-born": through his baptism in the Jordan he was regenerated and reborn from water and spirit. Consequently, in the Roman liturgy the font is designated the "uterus ecclesiae," and, as you can read in the Roman missal, it is called this even today, in the "benediction of the font" on Holy Saturday before Easter. Further, according to an early Christan-Gnostic idea, the spirit which appeared in the form of a dove was interpreted as Sophia-Sapientia-Wisdom and the Mother of Christ. Thanks to this motif of the dual birth, children today, instead of having good and evil fairies who magically "adopt" them at birth with blessings or curses, are given sponsors-a "god-father" and a "godmother."
The idea of a second birth is found at all times and in all places. In the earliest beginnings of medicine it was a magical means of healing; in many religions it is the central mystical experience; it is the key idea in medieval, occult philosophy, and, last but not least, it is an infantile fantasy occurring in numberless children, large and small, who believe that their parents are not their real parents but merely foster-parents to whom they were handed over. Benvenuto Cellini also had this idea, as he himself relates in his autobiography.
Now it is absolutely out of the question that all the individuals who believe in a dual descent have in reality always had two mothers, or conversely that those few who shared Leonardo's fate have infected the rest of humanity with their complex. Rather, one cannot avoid the assumption that the universal occurrence of the dual-birth motif together with the fantasy of the two mothers answers an omnipresent human need which is reflected in these motifs. If Leonardo da Vinci did in fact portray his two mothers in St. Anne and Mary-which I doubt-he nonetheless was only expressing something which countless millions of people before and after him have believed. The vulture symbol (which Freud also discusses in the work mentioned) makes this view all the more plausible. With some justification he quotes as the source of the symbol the Hieroglyphica of Horapollo, a book much in use in Leonardo's time. There you read that vultures are female only and symbolize the mother. They conceive through the wind (pneuma). This word took on the meaning of "spirit" chiefly under the influence of Christianity. Even in the account of the miracle at Pentecost the pneuma still has the double meaning of wind and spirit. This fact, in my opinion, points without doubt to Mary, who, a virgin by nature, conceived through the pneuma, like a vulture. Furthermore, according to Horapollo, the vulture also symbolizes Athene, who sprang, unbegotten, directly from the head of Zeus, was a virgin, and knew only spiritual motherhood. All this is really an allusion to Mary and the rebirth motif. There is not a shadow of evidence that Leonardo meant anything else by his picture. Even if it is correct to assume that he identified himself with the Christ-child, he was in all probability representing the mythological dual-mother motif and by no means his own personal prehistory. And what about all the other artists who painted the same theme? Surely not all of them had two mothers?
Let us now transpose Leonardo's case to the field of the neuroses, and assume that a patient with a mother complex is suffering from the delusion that the cause of his neurosis lies in his having really had two mothers. The personal interpretation would have to admit that he is right-and yet it would be quite wrong. For in reality the cause of his neurosis would lie in the reactivation of tile dual-mother archetype, quite regardless of whether he had one mother or two mothers, because, as we have seen, this archetype functions individually and historically without any reference to the relatively rare occurrence of dual motherhood.
In such a case, it is of course tempting to presuppose so simple and personal a cause, yet the hypothesis is not only inexact but totally false. It is admittedly difficult to understand how a dual-mother motif-unknown to a physician trained only in medicine-could have so great a determining power as to produce the effect of a traumatic condition. But if we consider the tremendous powers that lie hidden in the mythological and religious sphere in man, the aetiological significance of the archetype appears less fantastic. In numerous cases of neurosis the cause of the disturbance lies in the very fact that the psychic life of the patient lacks the co-operation of these motive forces. Nevertheless a purely personalistic psychology, by reducing everything to personal causes, tries its level best to deny the existence of archetypal motifs and even seeks to destroy them by personal analysis. I consider this a rather dangerous procedure which cannot be justified medically. Today you can judge better than you could twenty years ago the nature of the forces involved. Can we not see how a whole nation is reviving an archaic symbol, yes, even archaic religious forms, and how this mass emotion is influencing and revolutionizing the life of the individual in a catastrophic manner? The man of the past is alive in us today to a degree undreamt of before the war, and in the last analysis what is the fate of great nations but a summation of the psychic changes in individuals?
So far as a neurosis is really only a private affair, having its roots exclusively in personal causes, archetypes play no role at all. But if it is a question of a general incompatibility or an otherwise injurious condition productive of neuroses in relatively large numbers of individuals, then we must assume the presence of constellated archetypes. Since neuroses are in most cases not just private concerns, but social phenomena, we must assume that archetypes are constellated in these cases too. The archetype corresponding to the situation is activated, and as a result those explosive and dangerous forces hidden in the archetype come into action, frequently with unpredictable consequences. There is no lunacy people under the domination of an archetype will not fall a prey to. If thirty years ago anyone had dared to predict that our psychological development was tending towards a revival of the medieval persecutions of the Jews, that Europe would again tremble before the Roman fasces and the tramp of legions, that people would once more give the Roman salute, as two thousand years ago, and that instead of the Christian Cross an archaic swastika would lure onward millions of warriors ready for death-why, that man would have been hooted at as a mystical fool. And today? Surprising as it may seem, all this absurdity is a horrible reality. Private life, private aetiologies, and private neuroses have become almost a fiction in the world of today. The man of the past who lived in a world of archaic "reprsentaLions collectives" has risen again into very visible and painfully real life, and this not only in a few unbalanced individuals but in many millions of people.
There are as many archetypes as there are typical situations in life. Endless repetition has engraved these experiences into our psychic constitution, not in the form of images filled with content, but at first only as forms without content, representing merely the possibility of a certain type of perception and action. When a situation occurs which corresponds to a given archetype, that archetype becomes activated and a compulsiveness appears, which, like an instinctual drive, gains its way against all reason and will, or else produces a conflict of pathological dimensions, that is to say, a neurosis.
'We must now turn to the question of how the existence of archetypes can be proved. Since archetypes are supposed to produce certain psychic forms, we must discuss how and where one can get hold of the material demonstrating these forms. The main source, then, is dreams) which have the advantage of being involuntary, spontaneous products of the unconscious psyche and are therefore pure products of nature not falsified by any conscious purpose. By questioning the individual one can ascertain which of the motifs appearing in the dream are known to him. From those which are unknown to him we must naturally exclude all motifs which might be known to him, as for instance-to revert to the case of Leonardo-the vulture symbol. We are not sure whether Leonardo took this symbol from Horapollo or not, although it would have been perfectly possible for an educated person of that time, because in those days artists were distinguished for their wide knowledge of the humanities. Therefore, although the bird motif is an archetype par excellence, its existence in Leonardo's fantasy would still prove nothing. Consequently, we must look for motifs which could not possibly be knovn to the dreamer arid yet behave functionally in his dream in such a manner as to coincide with the functioning of the archetype known from historical sources.
Another source for the material we need is to be found in "active imagination." By this I mean a sequence of fantasies produced by deliberate concentration. I have found that the existence of unrealized, unconscious fantasies increases the frequency and intensity of dreams, and that when these fantasies are made conscious the dreams change their character and become weaker and less frequent. From this I have drawn the conclusion that dreams often contain fantasies which "want" to become conscious. The sources of dreams are often repressed instincts which have a natural tendency to influence the conscious mind. In cases of this sort, the patient is simply given the task of contemplating any one fragment of fantasy that seems significant to him-a chance idea, perhaps, or something he has become conscious of in a dream-until its context becomes visible, that is to say, the relevant associative material in which it is embedded. It is not a question of the "free association" recommended by Freud for the purpose of dream-analysis, but of elaborating the fantasy by observing the further fantasy material that adds itself to the fragment in a natural manner.
This is not the place to enter upon a technical discussion of the method. Suffice it to say that the resultant sequence of fantasies relieves the unconscious and produces material rich in archetypal images and associations. Obviously, this is a method that can only be used in certain carefully selected cases. The method is not entirely without danger, because it may carry the patient too far away from reality. A warning against thoughtless application is therefore in place.
Finally, very interesting sources of archetypal material are to be found in the delusions of paranoiacs, the fantasies observed in trance-states, and the dreams of early childhood, from the third to the fifth year. Such material is available in profusion, but it is valueless unless one can adduce convincing mythological parallels. It does not, of course, suffice simply to connect a dream about a snake with the mythological occurrence of snakes, for who is to guarantee that the functional meaning of the snake in the dream is the same as in the mythological setting? In order to draw a valid parallel, it is necessary to know the functional] meaning of the individual symbol, and then to find out whether the apparently parallel mythological symbol has a similar context and therefore the same functional meaning. Establishing such facts not only requires lengthy and wearisome researches, but is also an ungrateful subject for demonstration. As the symbols must not be torn out of their context, one has to launch forth into exhaustive descriptions, personal as well as symbological, and this is practically impossible in the framework of a lecture. I have repeatedly tried it at the risk of sending one half of my audience to sleep.
I am choosing as an example a case which, though already published, I use again because its brevity makes it peculiarly suitable for illustration. Moreover, I can add certain remarks which were omitted in the previous publication.
About 1906 I came across a very curious delusion in a paranoid schizophrenic who had been interned for many years. The patient had suffered since his youth and was incurable. He had been educated at a State school and been employed as a clerk in an office. He had no special gifts, and I myself knew nothing of mythology or archaeology in those days, so the situation was not in any way suspect. One day I fund the patient standing at the window, wagging his head and blinking into the sun. He told me to do the same, for then I would see something very interesting. When I asked him what he saw, he was astonished that I could see nothing, and said: "Surely you see the sun's penis-when I move my head to and fro, it moves too, and that is where the wind comes from." Naturally I did not understand this strange idea in the least, but I made a note of it. Then about four years later, during my mythological studies, I came upon a book by the late Albrecht Dieterich, the well-known philologist, which threw light on this fantasy. The work, published in 1910, deals with a Greek papyrus in the Bibliotheque Nationale, Paris. Dieterich believed he had discovered a Mithraic ritual in one part of the text. The text is undoubtedly a religious prescription for carrying out certain incantations in which Mithras is named. It comes from the Alexandrian school of mysticism and shows affinities with certain passages in the Leiden papyri and the Corpus Hermeticum. In Dieterich's text we read the following directions:
Draw breath from the rays, draw in three times as strongly as you can and you will feel yourself raised up and walking towards the height, and you will seem to be in the middle of the aerial region.
The path of the visible gods will appear through the disc of the sun. who is God my father- Likewise the so-called tube, the origin of the ministering wind. For you will see hanging down from the disc of the sun something that looks like a tube. And towards the regions westward it is as though there were an infinite east wind. But if the other wind should prevail towards the regions of the east, you will in like manner see the vision veering in that direction.
It is obviously the author's intention to enable the reader to experience the vision which he had, or which at least lie believes in. The reader is to be initiated into the inner religious experience either of the author, or-what seems more likely-of one of those mystic communities of which Philo Judaeus gives contemporary accounts. The fire- or sun-god here invoked is a figure which has close historical parallels, for instance with the Christ-figure of the Apocalypse. It is therefore a "representation collective," as are also the ritual actions described, such as the imitating of animal noises, etc. The vision is embedded in a religious context of a distinctly ecstatic nature and describes a kind of initiation into mystic experience of the Deity.
Our patient was about ten years older than I. In his megalomania, he thought he was God and Christ in one person. His attitude towards me was patronizing; he liked me probably because I was the only person with any sympathy for his abstruse ideas. His delusions were mainly religious, and when he invited me to blink into the sun like he did and waggle my head he obviously wanted to let me share his vision, He played the role of the mystic sage and I was the neophyte. He felt he was the sun-god himself, creating the wind by wagging his head to and fro. The ritual transformation into the Deity is attested by Apuleius in the Isis mysteries, and moreover in the form of a Helios apotheosis. The meaning of the "ministering wind" is probably the same as the procreative pneuma, which streams from the sun-god into the soul and fructifies it. The association of sun and wind frequently occurs in ancient symbolism.
It must now be shown that this is not a purely chance coincidence of two isolated cases. We must therefore show that the idea of a wind-tube connected with God or the sun exists independently of these two testimonies and that it occurs at other times and in other places. Now there are, as a matter of fact, medieval paintings that depict the fructification of Mary with a tube or hose-pipe coming down from the throne of God and passing into her body, and we can see the dove or the Christ-child flying down it. The dove represents the fructifying agent, the wind of the Holy Ghost.
'Now it is quite Out of the question that the patient could have had any knowledge whatever of a Greek papyrus published four years later, and it is in the highest degree unlikely that his vision had anything to do with the rare medieval representations of the Conception, even if through some incredibly improbable chance he had ever seen a copy of such a painting. The patient was certified in his early twenties. He had never travelled. And there is no such picture in the public art gallery in Zurich, his native town.
I mention this case not in order to prove that the vision is an archetype but only to show you my method of procedure in the simplest possible form. If we had only such Cases, the task of investigation would be relatively easy, but in reality the proof is much more complicated. First of all, certain symbols have to be isolated clearly enough to be recognizable as typical phenomena, not just matters of chance. This is done by examining a series of dreams, say a few hundred, for typical figures, and by observing their development in the series. The same method can be applied to the products of active imagination. In this way it is possible to establish certain continuities or modulations of one and the same figure. You can select any figure which gives the impression of being an archetype by its behaviour in the series of dreams or visions. If the material at one's disposal has been well observed and is sufficiently ample, one can discover interesting facts about the variations undergone by a single type. Not only the type itself but its variants too can be substantiated by evidence from comparative mythology and ethnology. I have described the method of investigation elsewhere  and have also furnished the necessary case material.
 [Originally given as a lecture to the Abernethian Society at St. Bartholomew's Hospital, London, on Oct. 19, i9~6, and published in the Hospital's Journal, XLIV (s9~6/~7), 4~49, 64-66. The present version has been slightly revised by the author and edited in terminology.-EWTOaS.]
 Leonado da Vinci and Memory of His Childhood sec. IV. Translated by Alan Tyson in Sigmund Freud, Standard Edition of the Complete Psychological Works, II (London, 1957)
 fCf. the trans. by George Boas, pp. 58ff.. and Freud, LoardG, Sec, II.---EDITOR.
 Wadlugen und Symbole der Libido (orig. 1912). [Trans. as Psychology of the Unconscious, 1916. Cf. the revised edition, Symbols of Tranformation, pars. 149ff., 1,23.EDIT0R£.]
 Eme Mithrasliturgie. [As the author subsequently learned, the 19t0 edition was actually the second, there having been a first edition in 1903. The patient had, however, been committed some years before 1905.-EDITOSS.]
 lbid., pp. 6ff.
 Psychology and Alchemy, Par II.