“The truth is that adaptation explains the sinuosities of the movement of Evolution, but not the general directions of the movement, still less the movement itself.  The road which leads to the town is obliged to follow the ups and downs of the hills; it adapts itself to the accidents of the ground, but the accidents of the ground are not the cause of the road nor have they given it its direction.” [Footnote:  Creative Evolution, p. 108 (Fr. p. 112).] The evolution of life cannot be explained as merely a series of adaptations to accidental circumstances.  Moreover, the mechanistic view, where all is “given,” is quite inadequate to explain the facts.  The finalist or teleological conception is not any more tenable, for Evolution is not simply the realization of a plan.  “A plan is given in advance.  It is represented or at least representable, before its realization.  The complete execution of it may be put off to a distant future or even indefinitely, but the idea is none the less formulable at the present time, in terms actually given.  If, on the contrary, Evolution is a creation unceasingly renewed, it creates as it goes on, not only the forms of life but the ideas that enable the intellect to understand it.  Its future overflows its present and cannot be sketched out therein, in an idea.  There is the first error of finalism.  It involves another yet more serious.  If life realizes a plan it ought to manifest a greater harmony the further it advances, just as the house shows better and better the idea of the architect as stone is set upon stone.” [Footnote:  Creative Evolution, p. 108 (Fr. p. 112).] Such finalism is really reversed mechanism.  If, on the contrary, the unity of life is to be found solely in the impetus (poussee formidable) that pushes it along the road of Time, the harmony is not in front but behind.  The unity is derived from a vis a tergo:  it is given at the start as an impulsion, not placed at the end as an attraction, as a kind of

     “... far-off divine event
      To which the whole creation moves.”

“In communicating itself the impetus splits up more and more.  Life, in proportion to its progress, is scattered in manifestations which undoubtedly owe to their common origin the fact that they are complementary to each other in certain aspects, but which are none the less mutually incompatible and antagonistic.  So that the discord between species will go on increasing.”  “There are species which are arrested, there are some that retrogress.  Evolution is not only a movement forward; in many cases we observe a marking-time, and still more often a deviation or turning back.  Thence results an increasing disorder.  No doubt there is progress, if progress means a continual advance in the general direction determined by a first impulsion; but this progress is accomplished only on the two or three great lines of Evolution on which forms ever more and more complex, ever more and more high, appear;