If, then, a phenomenon admits of a complete mechanical explanation, it will admit of an infinity of others, that will render an account equally well … - Henri Poincaré

Let us try to represent the figure formed by these two curves and their intersections in infinite number, each corresponding to a doubly asymptotic solution, these intersections form a kind of mesh, of fabric, of infinitely tight network; each of the two curves must never intersect itself, but it must fold back on itself in a very complex way in order to cross an infinite number of times all the meshes of the network. On will be struck by the complexity of this figure, which I do not even try to draw. Nothing is more likely to give us an idea of the complexity of the three-body problem and in general of all the problems of dynamics where there is no uniform integral and where the Bohlin series are divergent.

Each muscle gives rise to a special sensation capable of augmenting or of diminishing, so that the totality of our muscular sensations will depend upon as many variables as we have muscles. From this point of view, motor space would have as many dimensions as we have muscles.

Le plus grand hasard est la naissance d’un grand homme. Ce n’est que par hasard que se sont rencontrées deux cellules génitales, de sexe différent, qui contenaient précisément, chacune de son côté, les éléments mystérieux dont la réaction mutuelle devait produire le génie. On tombera d’accord que ces éléments doivent être rares et que leur rencontre est encore plus rare. Qu’il aurait fallu peu de chose pour dévier de sa route le spermatozoïde qui les portait ; il aurait suffi de le dévier d’un dixième de millimètre et Napoléon ne naissait pas et les destinées d’un continent étaient changées. Nul exemple ne peut mieux faire comprendre les véritables caractères du hasard.