The actual reproduction or remembrance of a fact--the demonstration or realisation of memory--undoubtedly depends on brain and muscle mechanism; but memory itself turns out to be essentially mental, and is found to exist apart from the bodily mechanism which helped originally to receive and store the impression. And though without that same or some equivalent mechanism we cannot get at it, so that it cannot be displayed to others, yet in my experience it turns out not to be absolutely necessary to use actually the same instrument for its reproduction as was responsible for its deposition: though undoubtedly to use the same is easier and helpful. In the early Edison phonographs the same instrument had to be used for both reception and reproduction; but now a record can readily be transferred from one instrument to another. This may be regarded as a rough mechanical analogy to the telepathic or telergic process whereby a psychic reservoir of memory can be partially tapped through another organism. But, apart from any consideration of what may be regarded as doubtful or uncertain, there are some facts about the relation of brain to consciousness, which, though universally admitted, are frequently misinterpreted. Injure the brain, and consciousness is lost. 'Lost' is the right word--not 'destroyed.' Repair the lesion, and consciousness may be restored, i.e. normal manifestation of consciousness can once more occur. It is the _display_ of consciousness, in all such cases, that we mean when we speak of the effect of brain injury; the utilisation of bodily organs is necessary for its exhibition. If the bodily organs do not exist, or are too damaged, no normal manifestation is possible. That is the fact which may be misinterpreted. In general we may say, with fair security, that no receptivity to physical phenomena exists save through sense-organ, nerve, and brain; nor any initiation of physical phenomena, save through brain, nerve, and muscle. Apart from physical phenomena consciousness is isolated and inaccessible: we have no right to say that it is non-existent. In ordinary usage it is not customary or necessary to be always harping on this completer aspect of things: it is only necessary when misunderstanding has arisen from uniformly inaccurate, or rather unguarded, modes of expression. In an excellent lecture by Dr. Mott on "The Effects of High Explosives upon the Central Nervous System," I find this sentence:-- "It is known that a continuous supply of oxygen is essential for consciousness." What is intended is clear enough, but analysed strictly this assertion goes far beyond what is known. We do not really know that oxygen, or any form of matter, has anything to do with consciousness: all that we know, and all that Dr. Mott really means to say, I presume, is that without a supply of oxygen consciousness gives no physical sign.