SUMMING UP.
Let us collect together the doctrines of the preceding chapters.
131. Time is a question difficult to explain. Whoever denies this difficulty shows that he has meditated but superficially on the matter.
132. Motion is measured by time; but it is not a sufficient definition of time to call it the measure of motion.
133. It is impossible to find a primitive measure of motion; we must, at last, take some measure or another, and although arbitrarily chosen, we must refer motion to it. It should be the most uniform measure possible.
134. The resemblance between the ideas of time and space creates a suspicion that they ought to be explained in a similar manner.
135. There is no duration without something which endures; therefore there is no duration separate from things. If nothing existed, there could be no duration.
136. There is no succession without things which succeed: therefore succession cannot be realized as a form independent of things, although it may be conceived in the abstract by itself.
137. Time impliesbeforeandafter, and, consequently, succession. It is succession itself, because in conceiving succession, we conceive time.
138. Succession involves the exclusion of some things by others. This exclusion may either be founded on the essence of things, or be derived from an external cause.
139. Time, therefore, involves exclusion: it is the general idea of the order of changes, or of the mutual relation of being and not-being.
140. If there were no change there would be no time.
141. No time had passed before the existence of the world. There was no other duration than eternity.
142. Eternity is the existence of the infinite being, without any alteration either actual or possible.
143. Time is not any thing absolute and independent of things, but is really in them. It is the order between being and not-being.
144. Co-existence is merely the existence of various beings. To conceive many beings without the idea of the negation of being, is to have the perception of co-existence.
145. Time may be considered under three aspects; the present, the past, and the future. All other relations of time, differently expressed in different idioms, are only combinations of these.
146. The present is the only absolute time: it is conceived without relation to the past or the future; but the past and the future are not conceived without relation to the present.
147. The idea of present accompanies the very idea of being; or rather, it is confounded with the idea of existence; that which has no present existence is not being.
148. The idea of past time is the perception of not-being, or of a being that has been destroyed, in relation to a present being: the idea of future time is the perception of apossible being proceeding from a cause already determined, and in relation to a present being.
149. The idea of time is excited by experience; but it cannot be called a fact of mere observation; for this would be opposed to its intrinsic necessity, by virtue of which it is the object of the exact sciences.
150. Still less can we say, that this idea is confined to the sensible order, since it includes every manner of change in general, whether sensible or supersensible.
151. The idea of time being the perception of the order between being and not-being, this relation, considered in general, belongs to the pure intellectual order. The transition to experience is realized in the same manner as in other general and indeterminate conceptions.
152. It is necessary to make a distinction between pure ideal time and empirical time: pure ideal time is the relation between being and not-being, considered in the greatest generality and the most complete indeterminateness; empirical time is the same relation subjected to a sensible measure.
153. To measure this succession, three things are necessary, and their union forms the idea of empirical time. They are, first, the pure idea of being and not-being, or of change; secondly, the application of this idea to a sensible phenomenon, as, for example, the solar motion; and thirdly, the idea of number applied to the determining of the changes of this phenomenon.
154. We thus conceive why empirical time implies a true necessity, and is the object of science. Of the three elements which compose it, the first is a metaphysical idea, the second, a mathematical idea, and the third, a fact of observation, to which these ideas are applied. If this fact be not real, it must, at least, be possible, in order to save the necessity of the calculation which is based upon it.
155. There is a close relation between the idea of time and the principle of contradiction. Each is explained by the other, yet this is not a vicious circle. The principle of contradiction consists in the mutual exclusion of being and not-being, and the idea of time is the perception of the order between being and not-being. Analysis must therefore lead to a part which is identical in both, to the comparison of the ideas of being and not-being.
156. Without the idea of time, memory would be impossible; consequently also, the unity of consciousness.