θαυτóς εστυ όkόσα εγερθευτες όρεμευ, όkόσα δε ευδoυες, υπυoς.

- Heraclitus.

200. Of the race of man we know for certain that it has been evolved through many ages and through countless forms of change. We know for certain that its changes continue still; nay, that more causes of change act upon us in "fifty years of Europe" than in "a cycle of Cathay." We may reasonably conjecture that the race will continue to change with increasing rapidity, and through a period in comparison with which our range of recorded history shrinks into a moment.

The actual nature of these coming changes, indeed, lies beyond our imagination. Many of them are probably as inconceivable to us now as eyesight would have been to our eyeless ancestors. All that we can do is to note so far as possible the structural laws of our personality as deduced from its changes thus far; inferring that for some time to come, at any rate, its further changes will proceed upon similar lines.

I have already (Chapter I (Introduction. Human Personality And Its Survival Of Bodily Death).) indicated the general view as to the nature of human personality which is maintained in this work. I regard each man as at once profoundly unitary and almost infinitely composite, as inheriting from earthly ancestors a multiplex and "colonial " organism - polyzoic and perhaps polypsychic in an extreme degree; but also as ruling and unifying that organism by a soul or spirit absolutely beyond our present analysis - a soul which has originated in a spiritual or metetherial environment; which even while embodied subsists in that environment; and which will still subsist therein after the body's decay.

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 the 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.1

201. 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.

202. 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.

Many disturbances and disintegrations of the personality must presently fall to be described. But the reader who may follow me must remember the point of view from which I am writing. The aim of my analysis is not to destroy but to fulfil; - or say, rather, my hope is that observation of the ways in which the personality tends to disintegrate may suggest methods which may tend on the other hand to its more complete integration.

Such improvements upon the natural conditions of the organism are not unknown. Just as the study of hysteria deals mainly with instabilities in the threshold of consciousness, so does the study of zymotic disease deal mainly with instabilities in the constitution of the blood. The ordinary object of the physician is to check these instabilities when they occur; to restore healthy blood in the place of vitiated. The experimental biologist has a further aim. He wishes to provide men with better blood than nature has bestowed; to elicit from virus and decay some element whose infusion into the veins may give immunity against microbic invasion. As the adult is safer against such attacks than the child by dint of his more advanced development, so is the immunised adult safer than the common man. The change in his blood which healthy maturity has induced has made him safe against whooping-cough. The change in his blood which we effect by injecting antitoxin makes him temporarily safe against diphtheria.

We have improved upon nature; - and our artifice has been prophylactic by virtue of being in a certain sense developmental.

1 The difficulty of conceiving any cellular focus, either fixed or shifting, has actually led some psychologists to demand a unifying principle which is not cellular, and yet is not a soul.

Even such, I trust, may be the achievement of experimental psychology in a later day. I shall be well content if in this chapter I (Introduction. Human Personality And Its Survival Of Bodily Death) can give hints for some future colligation of such evolutive phenomena as may lurk amid a mass of phenomena mainly dissolutive - phenomena whose records are scattered and imperfect, and have as yet only in some few directions, and by quite recent writers, been collated or systematised on any definite plan.