In what follows, we shall have to consider: I. the origin of the idea of cause in experience; II. its generalisation, and passage from the individual subjective, to the objective form; III. its transformation as resulting from the work performed in the various sciences, its scission into two fundamental ideas: on the one hand, that of force, energy, active and effective power, cause in the true sense (_vera causa_), which tends more and more to become a postulate, an x, a metaphysical residuum; on the other, that of a constant and invariable succession, a fixed _relation_, which becomes the scientific form of the concept of cause, equivalent in all respects to the concept of law. I. Every one seems agreed, fundamentally at least, upon the empirical origin of the idea of cause. It is of internal, subjective origin; suggested to us by our motor activity. A being who was hypothetically perfectly passive, while seeing or feeling constant external sequences, would have no idea of causality. It would be superfluous to show, by multiplying our quotations, that spiritualists like Maine de Biran, empiricists like Mill, critics like Renouvier, all the schools in short, with varying formulæ, agree upon this point. At the same time it must not be overlooked that some writers attribute an exclusive privilege to the “will,” maintaining it to be the type of causality; whereas the assertion that “our own voluntary action is the exclusive source whence this idea is derived” is unjustifiable. If, with some authors, the word “will” is used in a large and vague sense, as designating all mental activity that is translated by movements, no objection can be raised. But if it be used in the proper, restricted sense, as meaning a fully conscious, deliberate act, resulting from motive, the statement cannot be accepted.[122] Volition is a state that makes its appearance somewhat tardily. It is preceded by a period of appetites, of needs, instincts, desires, passions; and all these facts of internal activity, translated into movements; are as apt as the “will” to engender the empirical notion of cause, i. e., transitive action, i. e., change produced: they have moreover the advantage of being anterior in chronological order.