It is imposed first of all by immediate evidence, for we cannot deny that the history of life is revealed to us under the aspect of a progress and an ascent. And this impulse implies initiative and choice, constituting an effort which we are not authorised by the facts to pronounce fatalistic: "A simple glance at the fossil species shows us that life could have done without evolution, or could have evolved only within very restricted limits, had it chosen the far easier path open to it of becoming cramped in its primitive forms; certain Foraminifera have not varied since the silurian period; the Lingulae, looking unmoved upon the innumerable revolutions which have upheaved our planet, are today what they were in the most distant times of the palaeozoic era." ("Creative Evolution", page 111.) Moreover, if, in us, life is indisputably creation and liberty, how would it not, to some extent, be so in universal nature? "Whatever be the inmost essence of what is and what is being made, we are of it: ("Revue de Metaphysique et de Morale", November 1911.) a conclusion by analogy is therefore legitimate. But above all, this conclusion is verified by its aptitude for solving problems of detail, and for taking account of observed facts, and in this respect I regret that I can only refer the reader to the whole body of admirable discussions and analyses drawn up by Mr Bergson with regard to "the plant and the animal," or "the development of animal life."" ("Creative Evolution", chapter ii.) As regards matter, two main laws stand out from the whole of our science, relative to its nature and its phenomena: a law of conservation and a law of degradation. On the one hand, we have mechanism, repetition, inertia, constants, and invariants: the play of the material world, from the point of view of quantity, offers us the aspect of an immense transformation without gain or loss, a homogeneous transformation tending to maintain in itself an exact equivalence between the departure and arrival point. On the other hand, from the point of view of quality, we have something which is being used up, lowered, degraded, exhausted: energy expended, movement dissipated, constructions breaking up, weights falling, levels becoming equalised, and differences effaced. The travel of the material world appears then as a loss, a movement of fall and descent. In addition, there is only a tendency to conservation, a tendency which is never realised except imperfectly; while, on the contrary, we notice that the failure of the vital impulse is most infallibly interpreted by the appearance of mechanism. Reality falling asleep or breaking up is the figure under which we finally observe matter: matter then is secondary. Finally, according to Mr Bergson, matter is defined as a kind of descent; this descent as the interruption of an ascent; this ascent itself as growth; and thus a principle of creation is at the base of things.