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 accessory kinds of consciousness which do not speak, but reveal their existence by the use of other modes of expression, of which the most frequent is writing.

This doubling or fractionation of the consciousness and personality have often been described in the case of hysterical subjects. They sometimes occur quite spontaneously, but mostly they require a little suggestion and cultivation. In any case, that they are produced in one way or other proves that they are possible, and, for the theory, this possibility is essential. Facts of this kind do not lead to a theory of the unconscious, but they enable us to understand how certain phenomena, unconscious in appearance, are conscious to themselves, because they belong to states of consciousness which have been separated from each other.

A third thesis, more difficult of comprehension than the other two, supposes that the consciousness may be preserved in an unconscious form. This is difficult to admit, because unconsciousness is the negation of consciousness. It is like saying that light can be preserved when darkness is produced, or that an object still exists when, by the hypothesis, it has been radically destroyed. This idea conveys no intelligible meaning, and there is no need to dwell on it.

We have not yet exhausted all the concepts whereby we may get to unconsciousness. Here is