The comparisons just now instituted showed us that hitherto we have not been using the word ‘_regression_’ in its general sense but in a quite specific one. If you give it its general sense, that of a reversion from a higher to a lower stage of development in general, then repression also ranges itself under regression; for repression can also be described as reversion to an earlier and lower stage in the development of a mental act. Only, in repression this retrogressive direction is not a point of any moment to us; for we also call it repression in a dynamic sense when a mental process is arrested before it leaves the lower stage of the Unconscious. Repression is thus a topographic-dynamic conception, while regression is a purely descriptive one. But what we have hitherto called ‘_regression_’ and considered in its relation to fixation signified exclusively the return of _the Libido_ to its former halting-places in development, that is, something which is essentially quite different from repression and quite independent of it. Nor can we call regression of the Libido a purely psychical process; neither do we know where to localize it in the mental apparatus; for though it may exert the most powerful influence upon mental life, the organic factor in it is nevertheless the most prominent. Discussions of this sort tend to be rather dry; therefore let us turn to clinical illustrations of them in order to get a more vivid impression of them. You know that the group of the transference neuroses consists principally of hysteria and the obsessional neurosis. Now in hysteria, a regression of the Libido to the primary incestuous sexual objects is without doubt quite regular, but there is little or no regression to an earlier stage of sexual organization. Consequently the principal part in the mechanism of hysteria is played by repression. If I may be allowed to supplement by a construction the certain knowledge of this neurosis acquired up to the present I might describe the situation as follows: The fusion of the component-impulses under the primacy of the genital zone has been accomplished; but the results of this union meet with resistance from the direction of the preconscious system with which consciousness is connected. The genital organization therefore holds good for the Unconscious, but not also for the preconscious, and this rejection on the part of the preconscious results in a picture which has a certain likeness to the state prior to the primacy of the genital zone. It is nevertheless actually quite different. Of the two kinds of regression of the Libido, that on to an earlier phase of sexual organization is much the more striking. Since it is absent in hysteria and our whole conception of the neuroses is still far too much dominated by the study of hysteria which came first in point of time, the significance of Libido-regression was recognized much later than that of repression. We may be sure that our points of view will undergo still