A still weaker side of Lamarck’s theory is certainly the decided influence which he attributes to the _actions_ and _habits_ of organised beings, so as to modify them by their own means. The pedantic caprice of his enemies has always hit on this point. “The habit of exercising an organ,” he says, “makes it acquire developments and dimensions which insensibly change it, so that in time it becomes very different. On the contrary, the faulty continual exercise of an organ impoverishes it gradually, and ends by destroying it.”[303] But it must not be thought that Lamarck gave an _appreciable_ alteration to the organ,--an alteration sufficiently rapid to be noticed by ourselves. If some passages of his works make the reader think so, it is plain that they are only the wanderings of a great mind, always weak on the side of the ideas which he has created, and which he cherishes. Lamarck knew very well that an _infinite time_ is the condition of unlimited variability.[304] Darwin is the direct successor of Lamarck, and, in our opinion, the success of his book both in England and France is an index of the progress which scientific ideas have made, since the days of Cuvier, in the path of liberty and independence. Darwin, like Lamarck, admits unlimited variety; he thinks that all animals must descend from four or five primitive types, and plants from about an equal number; he is almost disposed to admit but one primordial type for all organic nature.[305] Darwin, however, seems to us to have fallen into a grievous exaggeration, or error of interpretation, formerly laid to Lamarck’s charge, while he is at the same time defending an excellent cause. Without speaking here of the relationship (forced, in our opinion) which Darwin makes out between wild and domestic animals (of which we have before spoken), the learned Englishman seems to have accorded too much to individual action in the production of specific modification. He sees a powerful activity, which he calls _natural selection_, where we can only see absolute passiveness. We will explain what we mean: in the midst of this vital concurrence, which he has in part so well described,--in the midst of this immense struggle, where all which has life on our planet is engaged in combat one against the other, or against all, on this eternal field of battle, where the victors become the victims, Darwin supposes that an animal brings into the world with him, _by chance_, some psychological modification, or some anatomical disposition, which is individually advantageous to him in the great struggle for life; after this he will have a chance of being among the victors, of uniting himself to another animal as happily endowed by birth by having also conquered; they will together leave a numerous posterity, and there is every chance that some of the descendants of such a couple may inherit either the same instinctive disposition or the same conformation; definitively, and by the repeated action of