Spinoza has asserted that “all individual bodies are animate, though in different degrees(74).” Now it is to a great extent this diversity of degree on which the main interest turns. Yet it is well to remember that the abrupt and trenchant separations which popular practice loves are overridden to a deeper view by an essential unity of idea, reducing them to indifference. If, that is, we take seriously the Spinozist unity of Substance, and the continual correlation (to call it no more) of extension and consciousness therein, we cannot avoid the conclusion which even Bacon would admit of something describable as attraction and perception, something subduing diversity to unity. But whether it be well to name this soul or life is a different matter. It may indeed only be taken to mean that all true being must be looked on as a real unity and individuality, must, that is, be conceived as manifesting itself in organisation, must be referred to a self-centred and self-developing activity. But this—which is the fundamental thesis of idealism—is hardly all that is meant. Rather Spinoza would imply that all things which form a real unity must have life—must have inner principle and unifying reality: and what he teaches is closely akin to the Leibnitian doctrine that every substantial existence reposes upon a monad, a unity which is at once both a force and a cognition, a “representation” and an appetite or _nisus_ to act. When Fechner in a series of works(75) expounds and defends the hypothesis that plants and planets are not destitute of soul, any more than man and animals, he only gives a more pronounced expression to this idealisation or spiritualisation of the natural world. But for the moment the point to be noted is that all of this idealistic doctrine is an inference, or a development which finds its _point d’appui_ in the fact of sensation. And the problem of the Philosophy of Mind is just to trace the process whereby a mere shock of sensation has grown into a conception and a faith in the goodness, beauty and intelligence of the world.