By Henri Poincaré - Translated by Nicolae Sfetcu

Henri Poincaré is a mathematician, physicist, philosopher and engineer, born April 29, 1854 in Nancy and died July 17, 1912 in Paris. He has carried out works of major importance in optics and in infinitesimal calculus. His advances on the problem of the three bodies make him a founder of the qualitative study of systems of differential equations and chaos theory; he is also a major precursor of the theory of special relativity and the theory of dynamical systems. Henri Poincaré is considered one of the last great universal scholars, mastering all branches of mathematics of his time and some branches of physics.
This book gathers here various articles and lectures that Henri Poincaré himself intended to form the fourth volume of his works of philosophy of science. All the previous ones had already appeared in this collection. It would be useless to recall their prodigious success. The most illustrious of modern mathematicians has been an eminent philosopher, one of those whose books profoundly influence human thought. It is probable that if Henri Poincaré himself had published this volume, he would have modified certain details, removed some repetitions. But it seemed to us that the respect due to the memory of this great death forbade any editing of his text.