A very simple calculation shows that more than 25,000 years would elapse before the conclusion of the operation. Thus the sensation of red light, experienced by us in the course of a second, corresponds in itself to a succession of phenomena which, separately distinguished in our duration with the greatest possible economy of time, would occupy more than 250 centuries of our history. Is this conceivable? We must distinguish here between our own duration and time in general. In our duration,—the duration which our consciousness perceives,—a given interval can only contain a limited number of phenomena of which we are aware. Do we conceive that this content can increase; and when we speak of an infinitely divisible time, is it our own duration that we are thinking of?
As long as we are dealing with space, we may carry the division as far as we please; we change in no way, thereby, the nature of what is divided. This is because space, by definition, is outside us; it is because a part of space appears to us to subsist even when we cease to be concerned with it; so that, even when we leave it undivided, we know that it can wait, and that a new effort of our imagination may decompose it when we choose. As, moreover, it never ceases to be space, it always implies juxtaposition and consequently possible division. Abstract space is, indeed, at bottom, nothing but the mental diagram of infinite divisibility. But with duration it is quite otherwise. The parts of
