the idea in order to make it active. It will not be amiss, before passing from this subject, to take note of and to ponder that certainty which, in trying to recollect something, we have of our possession of what we are thus striving to gain consciously, though we are not conscious what it is. We have the clearest conviction that, although we have forgotten it, we still have it and may recover it. How comes it to pass that we are so sure of the existence of that of which we are not conscious? In the first place, it would appear to supply an argument in support of the theory that something has been left behind in the nerve-circuit ministering to the forgotten idea, in other words, retained by it, which differentiates it from other nerve-circuits, disposes it to a repetition of its former activity, and produces the conviction of a latent possession, even when it is not active, or at any rate not active enough to awaken consciousness. In the second place, it must be remembered that the forgotten idea had associations with other ideas, which are really part of its meaning; it may well be, therefore, that when these are active and occupy the attention, while it remains inactive and below the horizon of consciousness, there is a tendency or sort of effort to reopen the former paths of association, in order to their completeness--to make the circuit, so to speak; and that it is the consciousness of this tendency or effort which gives rise to the certainty which we have of something forgotten. Certain it is, that when a stimulus excites one of two movements which have taken place together or in succession on former occasions, there is a tendency, when the stimulus is powerful or continued, to the reproduction of the associated movement; there is a diffusion of the stimulus along the accustomed path to the associated motor centres, and a union of movements is the result. A piece of poetry which has been thoroughly learnt may be repeated mechanically, as a tune may be whistled, when the proper verbal movements have been once started; indeed, the repetition in such case is most successful when consciousness is not too much occupied with it; for it frequently happens, if we think about the words which we are repeating, we become uncertain and forget, and are obliged, in order to succeed, to begin again and allow the succession of movements to go on automatically. We impede the operation of the spontaneous memory, upon which we really depend, when, by maintaining the activity of a word in consciousness as attention, we hinder the propagation thereof to the associated nerve-circuits.