What occurs each time we have in consciousness merely the general term, is only a particular case of a very common psychological fact: as follows:—The useful work is carried on below consciousness, and above its surface only results, indications, or signs appear. The facts enumerated above are all taken from motor activity. Their equivalents abound in the domain of feeling. The “causeless” states of joy or sorrow, which are frequent in the sound man, and still more in the invalid, are only the translation into consciousness of ignored organic dispositions operating in obscurity. What gives intensity and duration to our passions is not the consciousness we have of them, but the depth of the roots by which they plunge into our being, and are organised in our viscera, and subsequently in our brain. They are no more than the expression of our constitution, permanent, or momentary. We might run over the whole province of psychology, with variations on the same theme. I do not propose to do so here, but would simply recall that every state of consciousness whatsoever (percept, image, idea, feeling, passion, volition) has its substrate; that the concept reduced to the bare word is but another case of the same kind, and in no wise peculiar: that to believe that there is nothing more than the word, because it alone exists in consciousness, is to seize only the superficial and visible part of the event,—perhaps, all things considered, the least part. This unconscious substratum, this organised and potential knowledge, gives not merely value, but an actual denotation to the word,—like harmonics superadded to the fundamental note. To conclude: we think not with words in the strict sense (_flatus vocis_) but with signs. Symbolic thought, which is a purely verbal operation, is sustained, co-ordinated, vivified, by potential knowledge and unconscious travail. To this it must be added that potential knowledge is a genus, of which the concept is only a species. All memory can be reduced to latent knowledge, organised, susceptible of revival, but all memory is not material for concepts. The man who knows many languages even when not speaking them, the naturalist capable of identifying millions of specimens while not classifying them, have a very extended potential knowledge, but it is all concrete. The potential knowledge which underlies concepts consists in a sum of characters, qualities, extracts, which are the less numerous in proportion as the concept approximates to pure symbolism: in other terms what underlies the concept is an abstract memory, a memory for abstracts.