INTRODUCTION

The history of the evolution of life, however incomplete it may still be, already allows us to glimpse how intelligence was constituted through an uninterrupted progression along a line that rises through the series of vertebrates to man. It shows us, in the faculty of understanding, an appendage of the faculty of action, an increasingly precise, complex, and flexible adaptation of the consciousness of living beings to the conditions of existence imposed upon them. From this should follow the consequence that our intelligence, in the narrow sense of the word, is destined to ensure the perfect insertion of our body into its environment, to represent the relationships of external things to one another, and finally to think about matter. This will indeed be one of the conclusions of this essay. We will see that human intelligence feels at home as long as it is left among inert objects, more especially among solids, where our action finds its fulcrum and our industry its tools of work. We will see that our concepts were formed in the image of solids, that our logic is primarily the logic of solids, and that, for this very reason, our intelligence triumphs in geometry, where...