Where, now, can the libido find the fixations which it must have in order to force its way through the suppressions? In the activities and experiences of infantile sexuality, in its abandoned component-impulses, its childish objects which have been given up. The libido again returns to them. The significance of this period of childhood is a double one; on the one hand, the instinctive tendencies which were congenital in the child first showed themselves at this time; secondly, at the same time, environmental influences and chance experiences were first awakening his other instincts. I believe our right to establish this bipartite division cannot be questioned. The assertion that the innate disposition plays a part is hardly open to criticism, but analytic experience actually makes it necessary for us to assume that purely accidental experiences of childhood are capable of leaving fixations of the libido. I do not see any theoretical difficulties here. Congenital tendencies undoubtedly represent the after-effects of the experiences of an earlier ancestry; they must also have once been acquired; without such acquired characters there could be no heredity. And is it conceivable that the inheritance of such acquired characters comes to a standstill in the very generation that we have under observation? The significance of infantile experience, however, should not, as is so often done, be completely ignored as compared with ancestral experiences or those of our adult years; on the contrary, they should meet with an especial appreciation. They have such important results because they occur in the period of uncompleted development, and because of this very fact are in a position to cause a traumatic effect. The researches on the mechanics of development by Roux and others have shown us that a needle prick into an embryonic cell mass which is undergoing division results in most serious developmental disturbances. The same injury to a larva or a completed animal can be borne without injury. The libido fixation of adults, which we have referred to as representative of the constitutional factor in the etiological comparison of the neuroses, can be thought of, so far as we are concerned, as divisible into two separate factors, the inherited disposition and the tendency acquired in early childhood. We know that a schematic representation is most acceptable to the student. Let us combine these relations as follows: Disposition as accidental Cause of the determined by experiences neurosis == libido fixation + (traumatic element) | +-------------------------+------------------------+ | | Sexual constitution Infantile experience (pre-historic experience)