The idea that conscious existence in a vehicle other than the physical body is possible even during life is borne out to some extent by the evidence of those who testify to having seen their own body, from outside, while in a state of unconsciousness. An interesting one is given in the above mentioned work. The narrator describes how as he lay in bed he felt a cold sensation creeping up his legs from the feet and gradually extending throughout his body. After this had gone on for some time he became momentarily unconscious and on coming to himself again "seemed to be walking on air" and to be entirely free from his body. He thought of a friend who was some hundreds of miles distant and in a few seconds he found himself in the presence of his friend in circumstances which he describes. His friend spoke to him but he could not stay. After much difficulty and perplexity he decided that he ought to return to his body and as soon as he had made up his mind on the point he found himself looking at his apparently dead body propped up in bed as he had been when this experience began. He tried to control it and in due course was able to do so and after a time successfully "re-embodied" himself apparently none the worse for his experiences. The credentials of this case are good, and it is important to note that the friend referred to wrote spontaneously to say that he had seen the narrator at the time and in the circumstances which the latter describes. For this reason it can hardly be dismissed as a mere hallucination or dream and it is relevant to the present discussion because the narrator saw his own body from outside and was apparently embodied all the time in a vehicle of some sort. Another somewhat similar and equally remarkable case is given in the same work. This I shall deal with in a later chapter. In view of the foregoing considerations, I think it fair to say that the idea of a non-physical vehicle of consciousness capable, under the proper conditions, of temporary detachment from the physical body, has strong claims to be adopted as a working hypothesis for future investigations even though it is too early, as yet, to accept it as a proven fact. It certainly seems to clear up certain cases of apparition and abnormal acquisition of information as to distant events, in a way which other theories do not do without being strained to an extent which I regard as unwarrantable. It seems probable that the chief reason why such an hypothesis has not been adopted before is simply the difficulty of conceiving the nature of such a vehicle. But this is overcome if we suppose that it is four-dimensional. The theory has, of course, its own attendant difficulties and I have no desire disingenuously to ignore them. First it may be asked: How does the percipient see the apparition? For four-dimensional objects are, _ex hypothesi_ invisible to three-dimensional sight.