We may consider Geometry as a first attempt at a study of the outside world.
It may be considered as a deductive system which reflects (in the sense explained above, that is of the existence of a correspondence, etc.) very well our experiences with some features of the outside world, namely features connected with the displacements of what we call rigid bodies. We see at once how much is left out in such a study; in the first place, time is almost entirely left out: in trying to bring into coincidence two triangles we are not interested in whether we move one slowly or rapidly; in describing a circle we are not concerned with uniformity of motion.
