But there is no need to follow such a thorny path as this. Lillie sufficiently sums up the situation by declaring that “the universality of the rule of physical determination” as regards very minute, or “quantum” phenomena, is now subject to question; and that “in the highest manifestations of life, prediction [that is, the discovery of a mechanical law governing conduct] is not possible at all.” And he adds: “It follows that the regularity of macroscopic [or large] phenomena, in which determinism is for all practical purposes complete and trustworthy, is in reality a _statistical regularity_.” What can he possibly mean? Here is in reality a flash of light in darkness, the gist of the whole matter, the way out, the explanation of a thousand riddles. And he must put it in such language as this! For a statistical regularity is of course nothing but the regularity to be observed in averages. Individuals vary in a way which groups do not. No one is compelled to commit suicide this year. If I do such a thing it will be because I am individually a fool. And nobody knows whether my good sense is going to last another twelvemonth or not. Yet every actuary in every life-insurance company’s office in the world knows how many people are going to commit suicide this year, and next year, and the year after; and the quota which each civilized country is going to furnish. Their knowledge may not be absolutely accurate as to the last digit. There is a very slight margin for mistake. But they are almost as certain of the figures as they are of the figures for last year, or the year before. Mass action is sufficiently regular to make calculations based upon a comparison of its future with its past exceedingly profitable. Groups, and groups alone, obey the Law of Conservation. It was group action observed among atoms which gave rise to the formulation of that law. Individuals behave capriciously, obeying the laws of their unique natures, laws known only to God. But it will be objected: is not man a mass of atoms, or a mass of whatever ultimate particles science finally arrives at? And the answer is an emphatic _no_. His body is such a mass, but it is so formed as to be controlled, in so far as its movements are voluntary, by an individual self whose inner essence is single. The only way to make group action out of one man’s conduct is to observe him over a long period of time. His average may be guessed at. But nobody can say how he will act in a new and unusual circumstance. 5. CHANCE