the real. But, in fact, there is for us nothing that is instantaneous. In all that goes by that name there is already some work of our memory, and consequently of our consciousness, which prolongs into each other, so as to grasp them in one relatively simple intuition, an endless number of moments of an endlessly divisible time. Now what is, in truth, the difference between matter as the strictest realism might conceive it, and the perception which we have of it? Our perception presents us with a series of pictorial, but discontinuous, views of the universe; from our present perceptions we could not deduce subsequent perceptions, because there is nothing in an aggregate of sensible qualities which foretells the new qualities into which they will change. On the contrary, matter, as realism usually posits it, evolves in such a manner that we can pass from one moment to the next by a mathematical deduction. It is true that, between this matter and this perception, scientific realism can find no point of contact, because it develops matter into homogeneous changes in space, while it contracts perception into unextended sensations within consciousness. But, if our hypothesis is correct, we can easily see how perception and matter are distinguished, and how they coincide. The qualitative heterogeneity of our successive perceptions of the universe results from the fact that each, in itself, extends over a certain depth of duration, and that memory condenses
