If one seek (it is not to be found, I think, in Bergson’s writings) an explanation of this abatement or diminution of the _élan vital_, this tendency toward rest, the problem turns into the very ancient problem of the polarity of being in subject and object. In Platonism, matter arises as product of an eternal antagonism between two coeval principles, the Idea and Not-being. Not-being is thus something efficient, something that is capable of entering as a factor, together with the Idea, into a product, the Sensible Object. The truth is, therefore, that Not-being is something very real: it _is_ something because it _does_ something. It is as real as the Idea, because it is as efficient as the Idea. And in the Bergsonian creative evolution there often seems just such an antagonism as this, between two coördinate, efficient, and therefore real principles. Thus: “The impetus of life ... is confronted with matter, that is to say, with the movement that is the inverse of its own.”[124] And: “Life as a whole ... will appear as a wave which rises, and which is opposed by the descending movement of matter.”[125] But, as with Plato, so with Bergson, dubbing the hated principle “Not-being” or “Negation of Positive Reality” hardly avails against the soundness of its claim to positivity. And the case is not different if the “_élan vital_” is a self-limited absolute instead of an eternal dualism: the philosopher’s selection of one of the two coefficients or poles of this self-polarized absolute, rather than the other, to be snubbed, is arbitrary, instinctive, personal. With Plato it is one, with Bergson the other; no logical principle determines it, in either case.