An instance of this occurred at one of the concerts of a distinguished pianist a few years since. No. 3 was the reigning personality, and she was herself a lover of music and an excellent critic. Beethoven's concerto in C major was on the programme, and was being performed in a most charming manner by soloist and orchestra. I was sitting near her in the box, when all at once I noticed a change in the expression of her face, which denoted the presence of No. 1. She listened with intense interest and pleasure to the performance, and at its close I spoke a few words to her, and she replied in her usual charming manner. It was No. 1 without doubt. Soon after, she leaned back in her chair, took two or three quick, short inspirations, and No. 3 was present again. She turned to me smiling and said: "So No. 1 came for her favorite concerto; wasn't it splendid that she could hear it?" I said: "Yes; but how did you know she was here?" "Oh, I sat on the front of the box," she said. "I heard the music, too, and I saw you speaking to her." The four cases here briefly outlined represent both sexes, two distinct nationalities, and widely-varying conditions in life. In each case one or more personalities crop out, so to speak, come to the surface, and become the conscious, active, ruling personality, distinct from the original self, having entirely different mental, moral, and even physical, characteristics; different tastes, and different sentiments and opinions; personalities entirely unknown to the original self, which no one acquainted with that original self had any reason to suppose existed in connection with that organization. The cases present so many points of similarity in their history as to render it probable, if not certain, that some common principle, law, or mental state underlies them all--some law which, if clearly defined, would be valuable in reducing to order the seemingly lawless mass of phenomena which constantly meets us in this new and but little explored field of research. It may be, also, that other mental states more frequently met with and more easily observed present points in common with these more striking and unusual ones; and that they also may assist us in finding the clue. CHAPTER VI. NATURAL SOMNAMBULISM--HYPNOTIC SOMNAMBULISM--DREAMS. The first of these more accessible conditions to claim attention is natural somnambulism, or sleep-walking. The phenomena of this peculiar state have been observed from time immemorial, and have always been looked upon as one of the most wonderful and interesting subjects in the domain of the old psychology.