  The application to physics is immediate: “Among all possible groups we have chosen one in particular, in order to refer to it all physical phenomena, just as we choose three coordinate axes in order to refer to them a geometrical figure” (ibid., p. 291). The choice of this particular group is motivated by its mathematical simplicity, but also by the fact that “there exist in nature some remarkable bodies which are called solids, and experience tells us that the different possible movements of these bodies are related to one another much in the same way as the different operations of the chosen group” (ibid.). These remarks of Poincaré signalled the beginning of conventionalism in the philosophy of science and provided its initial motivation.