Physicists believe that the Gaussian law has been proved in mathematics while mathematicians think that it was experimentally established in physics. - Henri Poincaré

Despite the employment of the most highly perfected methods, the raw results of our experience will always present the characteristics of the physical continuum with the contradiction which is inherent in it.

In reality, space is therefore amorphous, a flaccid form, without rigidity, which is adaptable to everything, it has no properties of its own. To geometrize is to study the properties of our instruments, that is, of solid bodies.

We do not have and cannot have any means of discovering whether or not we are carried along in a uniform motion of translation.