For this very reason, perhaps, he is more at home in natural history than in the exact sciences. He has the gift of observation, and can suggest vividly the actual appearance of natural processes, in contrast to the verbal paraphrase of these processes which is sometimes taken to explain them. He is content to stop at habit without formulating laws; he refuses to assume that the large obvious cycles of change in things can be reduced to mechanism, that is, to minute included cycles repeated _ad libitum_. He may sometimes defend this refusal by sophistical arguments, as when he says that mechanism would require the last stage of the universe to be simultaneous with the first, forgetting that the unit of mechanism is not a mathematical equation but some observed typical event. The refusal itself, however, would be honest scepticism enough were it made with no _arriere pensee_, but simply in view of the immense complexity of the facts and the extreme simplicity of the mechanical hypothesis. In such a situation, to halt at appearances might seem the mark of a true naturalist and a true empiricist not misled by speculative haste and the human passion for system and simplification. At the first reading, M. Bergson's _Evolution Creatrice_ may well dazzle the professional naturalist and seem to him an illuminating confession of the nature and limits of his science; yet a second reading, I have good authority for saying, may as easily reverse that impression. M. Bergson never reviews his facts in order to understand them, but only if possible to discredit others who may have fancied they understood. He raises difficulties, he marks the problems that confront the naturalist, and the inadequacy of explanations that may have been suggested. Such criticism would be a valuable beginning if it were followed by the suggestion of some new solution; but the suggestion only is that no solution is possible, that the phenomena of life are simply miraculous, and that it is in the tendency or vocation of the animal, not in its body or its past, that we must see the ground of what goes on before us.