In the external we find not duration but simultaneity.
What duration is there existing outside us? The present only, or, if we prefer the expression, simultaneity. No doubt external things change, but their moments do not succeed one another, if we retain the ordinary meaning of the word, except for a consciousness which keeps them in mind. We observe outside us at a given moment a whole system of simultaneous positions; of the simultaneities which have preceded them nothing remains. To put duration in space is really to contradict oneself and place succession within simultaneity. Hence we must not say that external things endure, but rather that there is in them some inexpressible reason in virtue of which we cannot examine them at successive moments of our own duration without observing that they have changed. But this change does not involve succession unless the word is taken in a new meaning: on this point we have noted the agreement of science and common sense.
Thus in consciousness we find states which succeed, without being distinguished from one another; and in space simultaneities which, without succeeding, are distinguished from one another, in the sense that one has ceased to exist when the other appears. Outside us, mutual externality without succession; within us, succession without mutual externality.
The idea of a measurable time arises from compromise between ideas of succession and externality.
Here again a compromise comes in. To the simultaneities, which constitute the external world, and, although distinct, succeed one another for our consciousness, we attribute succession in themselves. Hence the idea that things endure as we do ourselves and that time may be brought within space. But while our consciousness thus introduces succession into external things, inversely these things themselves externalize the successive moments of our inner duration in relation to one another. The simultaneities of physical phenomena, absolutely distinct in the sense that the one has ceased to be when the other takes place, cut up into portions, which are also distinct and external to one another, an inner life in which succession implies interpenetration, just as the pendulum of a clock cuts up into distinct fragments and spreads out, so to speak, lengthwise, the dynamic and undivided tension of the spring. Thus, by a real process of endosmosis we get the mixed idea of a measurable time, which is space in so far as it is homogeneity, and duration in so far as it is succession, that is to say, at bottom, the contradictory idea of succession in simultaneity.
As science eliminates duration from the outer, philosophy must eliminate space from the inner world.
Now, these two elements, extensity and duration, science tears asunder when it undertakes the close study of external things. For we have pointed out that science retains nothing of duration but simultaneity, and nothing of motion itself position of the moving body, i.e. immobility. A very sharp separation is here made and space gets the best of it.
Therefore the same separation will have to be made again, but this time to the advantage of duration, when inner phenomena are studied, —not inner phenomena once developed, to be sure, or after the discursive reason has separated them and set them out in a homogeneous medium in order to understand them, but inner phenomena in their developing, and in so far as they make up, by their interpenetration, the continuous evolution of a free person. Duration, thus restored to its original purity, will appear as a wholly qualitative multiplicity, an absolute heterogeneity of elements which pass over into one another.
The neglect to separate extensity and duration leads one party to deny freedom and the other to define it.