It is, of course, impossible for us to picture to ourselves the way in which the individual life of each cell of the body is reconciled with the unity of the central life which controls the body as a whole. But this difficulty is not created or intensified by the hypothesis of a separate and persistent soul. On no hypothesis can we really understand the collaboration and subordination of the cell-lives of any multicellular animal. It is as mysterious in the starfish as it is in Plato; and the "eight brains of Aurelia," with their individual and their common life, are as inconceivable as the life of the phagocytes in the philosopher's veins, in their relation to his central thought.[7] I claim, in fact, that the ancient hypothesis of an indwelling soul, possessing and using the body as a whole, yet bearing a real, though obscure relation to the various more or less apparently disparate conscious groupings manifested in connection with the organism and in connection with more or less localised groups of nerve-matter, is a hypothesis not more perplexing, not more cumbrous, than any other hypothesis yet suggested. I claim also that it is conceivably provable,--I myself hold it as actually proved,--by direct observation. I hold that certain manifestations of central individualities, associated now or formerly with certain definite organisms, have been observed in operation apart from those organisms, both while the organisms were still living, and after they had decayed. Whether or no this thesis be as yet sufficiently proved, it is at least at variance with no scientific principle nor established fact whatever; and it is of a nature which continued observation may conceivably establish to the satisfaction of all. The negative thesis, on the other hand, is a thesis in unstable equilibrium. It cannot be absolutely proved by any number of negative instances; and it may be absolutely disproved by a single positive instance. It may have at present a greater scientific _currency_, but it can have no real scientific authority as against the view defended in these pages. Leaving these questions, however, aside for the present, we may agree that in the organism as we can observe it in common life we have no complete or unchanging unity, but rather a complex hierarchy of groups of cells exercising vaguely limited functions, and working together with rough precision, tolerable harmony, fair success. That these powers ever work _perfectly_ together we have no evidence. Our feeling of health is but a rough haphazard register of what is passing within us. Nor would it ever be possible to define a permanently ideal status in an organism in moving equilibrium,--an organism which lives by exploding unstable compounds, and which is constantly aiming at new ends at the expense of the old.