Bergson’s differentiation of temporal succession from spatial seriality gets all its cogency from an exclusive attention, when consciousness is concerned, to the aspects of heterogeneity (quality) and compenetration (continuity) which consciousness shows; and, when space is concerned, to _its_ aspects of homogeneity (quantity) and juxtaposition of parts (discreteness). As always, with correlative abstractions, Bergson reifies them: they exclude each other, for him, whereas, in truth, they imply each other, entering into each other’s definition so that each is unthinkable except by means of the other. Time is continuous, Bergson insists rightly; but jumps to the conclusion that therefore time is not discrete. Time is heterogeneous, therefore not homogeneous. Space is discrete (its parts spread out), therefore not continuous; homogeneous, therefore not heterogeneous. If any demonstration is necessary that these terms do imply each other, instead of excluding each other, the case of heterogeneity and homogeneity is only the case of resemblance and difference (cf. page 44). In regard to the heterogeneity of space, its differentiation by way of direction must not be forgotten. As for the other pair of terms, continuity can manifest itself only _in extenso_, and discreteness requires a separating _medium_. Wherever Bergson objects to expressing time in terms of space, the real objection is to the expression of time in terms of homogeneity. This he would not only admit, but insist upon. But his demonstration that homogeneity is a character exclusively spatial is a _petitio principii_.[115] Of the attempt to measure a minute, he writes as follows: “I say, _e. g._, that a minute has just elapsed, and I mean by this that a pendulum, beating the seconds, has completed sixty oscillations. If I picture these sixty oscillations to myself all at once, by a single mental perception, I exclude by hypothesis the idea of a succession. I do not think of sixty strokes which succeed one another, but of sixty points on a fixed line, each one of which symbolizes, so to speak, an oscillation of the pendulum. If, on the other hand, I wish to picture these sixty oscillations in succession, but without altering the way they are produced in space, I shall be compelled to think of each oscillation to the exclusion of the recollection of the preceding one, for space has preserved no trace of it; but by doing so I shall condemn myself to remain forever in the present; I shall give up the attempt to think a succession or a duration.”