The meaning of Death depending, as has been said, on the meaning of Life, we must first set ourselves to grasp the leading characteristics which distinguish living things. To a physiologist the living organism is distinguished from the not-living by the performance of certain functions. These functions are four in number--Assimilation, Waste, Reproduction, and Growth. Nothing could be a more interesting task than to point out the co-relatives of these in the spiritual sphere, to show in what ways the discharge of these functions represent the true manifestations of spiritual life, and how the failure to perform them constitutes spiritual Death. But it will bring us more directly to the specific subject before us if we follow rather the newer biological lines of Mr. Herbert Spencer. According to his definition, Life is "The definite combination of heterogeneous changes, both simultaneous and successive, in correspondence with external co-existences and sequences,"[55] or more shortly "The continuous adjustment of internal relations to external relations."[56] An example or two will render these important statements at once intelligible.
The essential characteristic of a living organism, according to these definitions, is that it is in vital connection with its general surroundings. A human being, for instance, is in direct contact with the earth and air, with all surrounding things, with the warmth of the sun, with the music of birds, with the countless influences and activities of nature and of his fellow-men. In biological language he is said thus to be "in correspondence with his environment." He is, that is to say, in active and vital connection with them, influencing them possibly, but especially being influenced by them. Now it is in virtue of this correspondence that he is entitled to be called alive. So long as he is in correspondence with any given point of his environment, he lives. To keep up this correspondence is to keep up life. If his environment changes he must instantly adjust himself to the change. And he continues living only as long as he succeeds in adjusting himself to the "simultaneous and successive changes in his environment" as these occur. What is meant by a change in his environment may be understood from an example, which will at the same time define more clearly the intimacy of the relation between environment and organism. Let us take the case of a civil-servant whose environment is a district in India. It is a region subject to occasional and prolonged droughts resulting in periodical famines. When such a period of scarcity arises, he proceeds immediately to adjust himself to this external change. Having the power of locomotion, he may remove himself to a more fertile district, or, possessing the means of purchase, he may add to his old environment by importation the "external relations" necessary to continued life. But if from any cause he fails to adjust himself to the altered circumstances, his body is thrown out of correspondence with his environment, his "internal relations" are no longer adjusted to his "external relations," and his life must cease.
In ordinary circumstances, and in health, the human organism is in thorough correspondence with its surroundings; but when any part of the organism by disease or accident is thrown out of correspondence, it is in that relation dead.
This Death, this want of correspondence, may be either partial or complete. Part of the organism may be dead to a part of the environment, or the whole to the whole. Thus the victim of famine may have a certain number of his correspondences arrested by the change in his environment, but not all. Luxuries which he once enjoyed no longer enter the country, animals which once furnished his table are driven from it. These still exist, but they are beyond the limit of his correspondence. In relation to these things therefore he is dead. In one sense it might be said that it was the environment which played him false; in another, that it was his own organization--that he was unable to adjust himself, or did not. But, however caused, he pays the penalty with partial Death.