Page:The World as Will and Idea - Schopenhauer, tr. Haldane and Kemp - Volume 3.djvu/497

Rh. If space were their only form there would be no succession, and therefore no change. Time may therefore be defined as the possibility of mutually exclusive conditions of the same thing. But the union of these two forms of existence is the essential condition of reality, and this union is the work of the understanding (see "World as Will and Idea," vol. i. § 4, and the table of predicables annexed to vol. ii., chap. 4). In this class of objects for the subject the principle of sufficient reason appears as the law of causality or the principle of sufficient reason of becoming, and it is through it that all objects which present themselves in perception are bound together through the changes of their states. When a new state of one or more objects makes its appearance it must have been preceded by another on which it regularly follows. This is causal sequence, and the first state is the cause, the second the effect. The law has thus to do exclusively with the changes of objects of external experience, and not with things themselves, a circumstance which is fatal to the validity of the cosmological proof of the existence of God. It follows also from the essential connection of causality with succession that the notion of reciprocity, with its contemporaneous existence of cause and effect, is a delusion. The chain of causes and effects does not affect either matter, which is that in which all changes take place, or the original forces of nature, through which causation becomes possible, and which exist apart from all change, and in this sense out of time, but which yet are everywhere present (e.g., chemical forces, see supra, vol. i., § 26). In nature causation assumes three different forms; that of cause in the narrow sense, of stimulus, and of motive, on which differences depend the true distinctions between inorganic bodies, plants, )and animals. It is only of cause properly so called that Newton's third law of the equality of action and reaction is true, and only here do we find the degree of the effect proportionate to that of the cause. The absence of this feature characterises stimulation. Motive demands knowledge as its condition, and intelligence is therefore the true characteristic of the animal. The three forms are in principle identical, the difference being due to the degrees of receptivity in existence. What is called freedom