In the foregoing chapters I have considered the theory of Monism, first in contrast with the theories of Materialism and of Spiritualism, and next in relation to the theory of Theism. In this chapter and that which succeeds it I propose to consider Monism in relation to the Will. To do this it is needful to begin by considering the problems which are presented by the Will in relation to the older theories of Materialism on the one hand and of Spiritualism on the other. Although the phenomena of volition have occupied so large a province of philosophical literature, the fundamental problems which arise in connexion with them are only two in number, and both admit of being stated in extremely simple terms. The historical order in which these two problems have arisen is the inverse of their logical order. For while in logical order the two problems would stand thus--Is the Will an agent? If so, is it a free agent?--in actual discussion it was long taken for granted that the Will is an agent, and hence the only controversy gathered round the question whether the Will is a free agent. Descartes, indeed, seems to have entertained the prior question with regard to animals, and there are passages in the _Leviathan_ which may be taken to imply that Hobbes entertained this question with regard to man. But it was not until recent years that any such question could stand upon a basis of science as distinguished from speculation; the question did not admit of being so much as stated in terms of science until physiology was in a position openly to challenge our right to assume that the Will is an agent. Such a challenge physiology has now given, and even declared that any assumption of volitional agency is, in the presence of adequate physiological knowledge, impossible. The two problems which I thus state separately are often, and indeed generally, confused together; but for the purpose of clear analysis it is of the first importance that they should be kept apart. In order to show the wide distinction between them, we may best begin with a brief consideration of what it is that the two problems severally involve; and to do this we may best take the problems in what I have called their logical order.