There are in general two main views which may be taken about Vitality. We may either suppose that Life is purely a product of the body, that it is a mere physiological function and nothing more, or one may suppose that so far from the body being the primary cause of Life the exact converse is the case--that Life is the _raison d'etre_ of the body. It may be that everything that we recognize as "vital," every attribute which enables us to distinguish animate from inanimate objects, is no more than a purely physical phenomenon the product of unusually complicated chemical actions: or it may be that the chemico-physical complex which we call the body is only the means whereby the pressing tide of Life manages to manifest itself in the world. This latter is the view held by M. Bergson, by Mr. Carrington and by myself. "M. Bergson regards matter as the dam which keeps back the rush of life. Organise it a little (as in the protozoa), _i.e._, slightly raise the sluice,--and a little life will squeeze through. Organise it elaborately (as in man), _i.e._, raise the sluice a good deal, and much life will squeeze through." (The Right Hon. A.J. Balfour.) This is the "transmissive" as opposed to the "productive" theory and the whole position is very like that which obtained in Psychology some years ago. William James then showed that although it was possible to interpret the observed facts of Psychology on the hypothesis that the brain "produced" consciousness it was equally legitimate to do so on the hypothesis that it "transmitted" it. As he said " ... Mere coincidence in two sets of phenomena does not prove that they are causally connected, that one produces the other. They may be quite separate from one another (psycho-physical parallelism) or both may be aspects of something else." Personally I should be prepared to admit only the latter possibility. Causeless parallelism is incredible; as James himself admits elsewhere. The analogy is very close. Just as consciousness is usually conceived to be due to the functioning of the brain but may, on the contrary exist apart from it and merely use the brain as a channel of manifestation, so also may Life exist apart from and use the body. I will not go into the various arguments which support this view. Perhaps the most striking is that from the necessity for sleep--a phenomenon which appears to be exclusively associated with Life. A mechanism needs replenishing with fuel, it must have worn parts replaced and both these processes are accurately paralleled in the body of any living organism. But an engine does not need sleep, whereas a living organism not only needs it but cannot be satisfied with any substitute for it. It looks therefore as if Life could not be maintained from purely physical sources and this lends support to the view that it is an essentially extra-physical thing transmitted by, but not arising from, physical actions.