own origin in our normal mental life. All the qualities which we value in our thought-processes, and which mark them out as complicated performances of a high order, we shall find repeated in the dream-thoughts. There is, however, no need to assume that this mental work is performed during sleep; such an assumption would badly confuse the conception of the psychic state of sleep to which we have hitherto adhered. On the contrary, these thoughts may very well have their origin in the daytime, and, unremarked by our consciousness, may have gone on from their first stimulus until, at the onset of sleep, they have reached completion. If we are to conclude anything from this state of affairs, it can only be that it proves that the most complex mental operations are possible without the cooperation of consciousness- a truth which we have had to learn anyhow from every psycho-analysis of a patient suffering from hysteria or obsessions. These dream-thoughts are certainly not in themselves incapable of consciousness; if we have not become conscious of them during the day, this may have been due to various reasons. The act of becoming conscious depends upon a definite psychic function- attention- being brought to bear. This seems to be available only in a determinate quantity, which may have been diverted from the train of thought in question by other aims. Another way in which such trains of thought may be withheld from consciousness is the following: From our conscious reflection we know that, when applying our attention, we follow a particular course. But if that course leads us to an idea which cannot withstand criticism, we break off and allow the cathexis of attention to drop. Now, it would seem that the train of thought thus started and abandoned may continue to develop without our attention returning to it, unless at some point it attains a specially high intensity which compels attention. An initial conscious rejection by our judgment, on the ground of incorrectness or uselessness for the immediate purpose of the act of thought, may, therefore, be the cause of a thought-process going on unnoticed by consciousness until the onset of sleep.

Let us now recapitulate: We call such a train of thought a preconscious train, and we believe it to be perfectly correct, and that it may equally well be a merely neglected train or one that has been interrupted and suppressed. Let us also state in plain terms how we visualize the movement of our thought. We believe that a certain quantity of excitation, which we call cathectic energy, is displaced from a purposive idea along the association paths selected by this directing idea. A neglected train of thought has received no such cathexis, and the cathexis has been withdrawn from one that was suppressed or rejected; both have thus been left to their own excitations. The train of thought cathected by some aim becomes able under certain conditions to attract the attention of consciousness, and by the mediation of consciousness it then receives hyper-cathexis. We shall be obliged presently to elucidate our assumptions as to the nature and function of consciousness.

A train of thought thus incited in the Pcs may either disappear spontaneously, or it may continue. The former eventuality we conceive as follows: it diffuses its energy through all the association paths emanating from it, and throws the entire chain of thoughts into a state of excitation, which continues for a while, and then subsides, through the excitation which had called for discharge being transformed into dormant cathexis. If this first eventuality occurs, the process has no further significance for dream-formation. But other directing ideas are lurking in our preconscious, which have their source in our unconscious and ever- active wishes. These may gain control of the excitation in the circle of thoughts thus left to itself, establish a connection between it and the unconscious wish, and transfer to it the energy inherent in the unconscious wish. Henceforth the neglected or suppressed train of thought is in a position to maintain itself, although this reinforcement gives it no claim to access to consciousness. We may say, then, that the hitherto preconscious train of thought has been drawn into the unconscious.

Other constellations leading to dream-formation might be as follows: The preconscious train of thought might have been connected from the beginning with the unconscious wish, and for that reason might have met with rejection by the dominating aim- cathexis. Or an unconscious wish might become active for other (possibly somatic) reasons, and of its own accord seek a transference to the psychic residues not cathected by the Pcs. All three cases have the same result: there is established in the preconscious a train of thought which, having been abandoned by the preconscious cathexis, has acquired cathexis from the unconscious wish.