Its necessary condition is the trance or somnambulistic state. The sensitive falls asleep spontaneously, or is put to sleep artificially by passes. After a certain time, more or less long, and after diverse movements, the most usual of which seem to be muscular contractions of the face and pharynx, the sensitive enters into somnambulism and passes into the secondary state. Some subjects fall asleep very quickly. It is not a rare thing in spiritistic seances, for two or three persons to enter into a state of somnambulism at the same time. The perfection of the sensitive’s acting, when personifying diverse individualities, is most striking when they have known the persons they are imitating. Observation is extremely interesting. In spiritistic seances these personalities, naturally, always represent spirits. I have seen nothing in this order of phenomenon which appeared to me worth noting. Everything is easily explained by the play of impersonal memory and by imitation. Many transcendental facts have been related to me: personally I have observed none. But I have very rarely tried to provoke trance phenomena. They do not present the same interest to me as physical phenomena do. The most interesting I have seen, were given me by Madame Agullana, in private seances. This sensitive’s most curious personality is that of a doctor, who died about eighty or a hundred years ago: he has always refused to give any information concerning his identity; the reason he advances for maintaining his incognito—the existence of his family, members of whom are living in the south of France—does not satisfy me; I imagine he is withholding the best. His medical language is archaic. He calls plants by their ancient medical names; his diagnosis, accompanied with extra-ordinary explanations, is generally correct, but the description of the internal symptoms which he perceives is such as would astound a doctor of the twentieth century. Matters, fluids, molecules, dance a strange saraband. Nevertheless, my colleague from beyond the tomb—not at all loquacious, by the way—retains a serenity, which is proof against everything, and humbly recognises that there are many things he does not know. During the ten years I have been observing him, he has not changed, and presents a logical continuity which is most striking. Persons, who are not _au courant_ with the features of secondary personalities, might easily be deceived and believe in his objective reality. Be he what he says he is, or be he what I suspect him to be, that is to say, one of the sensitive’s secondary personalities, my _confrère_ Hippolytus is an interesting interlocutor, and, with his conversation, one could write a work on clinical medicine which would be rather out of the common. This is not the place to study him, for his examination only raises problems of psychological interest. In these phenomena of mixed automatism, of ‘incarnation,’ we observe the complete development of _personifications_.