We began this chapter with an expression of our full adhesion to the view which insists upon the uniformity, not merely of nature, but also of human nature. We rejected the idea that there is no science of man, and has been no evolution of mind, as a patent absurdity, and a violent contradiction of admitted facts. Any theory of evolution and any definition of science which fails to comprehend human nature is thereby condemned as inadequate and inaccurate. For those, then, who with us accept the continuity and uniformity between nature and man there will be no difficulty in arguing from the one to the other: which of the two we shall start from will depend mainly upon circumstances, upon which is the more accessible in any particular inquiry, and which is likely to afford the best "take-off." In the present case the action of inanimate objects upon one another can be accounted for on either hypothesis, _i.e._ that such action is willed by some superior power or that it is necessitated by some previous action, which is necessitated by some other previous action, and so on for ever, without ever reaching any original or originating necessity. Both hypotheses will fit all the facts of all the physical sciences; both _are_ hypotheses; and science can do and does do without either one or the other. Nor does our observation of the observed facts of nature enable us to say, with regard to any actual fact of this kind, either that it could or that it could not have happened otherwise than it did. In fine, as long as we confine ourselves to the subject-matter of the physical sciences, as long as we start in this case from nature, we cannot find anything to disturb the equal balance of the two hypotheses, which are two hypotheses and nothing more. But when we turn from nature to human nature, when we consult our own experience of our own actions, the case is notoriously different. Our experience in that case is that of two or more suggested and possible actions we are free to choose whichever we will; and our memory of past acts of choice testifies that though we actually chose one particular course, we might have abstained from it in favour of some other alternative. Here, too, as in the case of purely physical causation, the fact that a thing happened is proof conclusive that, in accordance with the law of universal causation, the conditions necessary to its occurrence were fulfilled; but it constitutes no proof or probability that the conditions were bound to be fulfilled. The fact that we chose to act in a certain way does not in the least convince us that we were bound to choose that action and that action alone. On the contrary, our memory is clear and our conviction is certain that our choice was free. In the physical and the spiritual spheres alike it is true that, when all the conditions requisite for a given effect are combined, the result must ensue. And in both spheres it is equally true