For many years there was one question which had continually obtruded itself upon his thoughts. All his experiments and his theories turned upon a single point. A hundred times a day the Professor asked himself whether it was possible for the human spirit to exist apart from the body for a time and then to return to it once again. When the possibility first suggested itself to him his scientific mind had revolted from it. It clashed too violently with preconceived ideas and the prejudices of his early training. Gradually, however, as he proceeded farther and farther along the pathway of original research, his mind shook off its old fetters and became ready to face any conclusion which could reconcile the facts. There were many things which made him believe that it was possible for mind to exist apart from matter. At last it occurred to him that by a daring and original experiment the question might be definitely decided. “It is evident,” he remarked in his celebrated article upon invisible entities, which appeared in the _Keinplatz wochentliche Medicalschrift_ about this time, and which surprised the whole scientific world--“it is evident that under certain conditions the soul or mind does separate itself from the body. In the case of a mesmerised person, the body lies in a cataleptic condition, but the spirit has left it. Perhaps you reply that the soul is there, but in a dormant condition. I answer that this is not so, otherwise how can one account for the condition of clairvoyance, which has fallen into disrepute through the knavery of certain scoundrels, but which can easily be shown to be an undoubted fact. I have been able myself, with a sensitive subject, to obtain an accurate description of what was going on in another room or another house. How can such knowledge be accounted for on any hypothesis save that the soul of the subject has left the body and is wandering through space? For a moment it is recalled by the voice of the operator and says what it has seen, and then wings its way once more through the air. Since the spirit is by its very nature invisible, we cannot see these comings and goings, but we see their effect in the body of the subject, now rigid and inert, now struggling to narrate impressions which could never have come to it by natural means. There is only one way which I can see by which the fact can be demonstrated. Although we in the flesh are unable to see these spirits, yet our own spirits, could we separate them from the body, would be conscious of the presence of others. It is my intention, therefore, shortly to mesmerise one of my pupils. I shall then mesmerise myself in a manner which has become easy to me. After that, if my theory holds good, my spirit will have no difficulty in meeting and communing with the spirit of my pupil, both being separated from the body. I hope to be able to communicate the result of this interesting experiment in an early number of the _Keinplatz wochenliche Medicalschrift_.”