In chapter III we have described some of the phenomena to be observed in various morbid states of mind, and in chapter IV we have endeavoured to arrange these phenomena into groups. This process of classification has enabled us to reduce the original chaos into some sort of order, and to obtain a comprehensive view of the facts of our subject. We have discovered, for example, that many of the manifestations of mental disorder are to be regarded as cases of dissociation of consciousness—the stream of consciousness is divided into independent currents no longer combined into one harmonious whole. So far, however, no attempt has been made to explain why these phenomena occur. We have seen that the imaginary voices which torture the hallucinated patient are nothing but split-off portions of his own consciousness, but we have assigned no reason to account for a portion of consciousness being split off in this abnormal manner, nor have we explained why the hallucinatory voice should make remarks of one character rather than another. We have found, in fact, that certain events occur, but we are still altogether in the dark as to why they occur.

The reader who has clearly understood the general principles enunciated in chapter II will at once perceive that we have carried out the first two steps of the method of science, but have as yet made no attempt to proceed to the third step.