None of our sensations, isolated, could have conducted us to the idea of space; we are led to it only in studying the laws, according to which these … - Henri Poincaré

only reach him after having traversed reflecting media of complicated form. The two indications which serve us in judging distances would cease to be connected by a constant relation. A being who should achieve in such a world the education of his senses would no doubt attribute four dimensions to complete visual space.

if the contrary takes place, if these two muscular sensations vary independently of one another, we shall have to take account of one more independent variable, and 'complete visual space' will appear to us as a physical continuum of four dimensions.

O societate este cu atât mai înaintată, cu cât are mai mare grijă faţă de bufonii ei.