Entre 1881 et 1911, Gosta Mittag-Leffler et Henri Poincare echangent une correspondance reguliere. Elle couvre quasiment la carriere scientifique de Poincare. Ce volume est le premier d'une edition commentee de la correspondance de Henri Poincare. Trois autres tomes sont en cours de preparation: le second sera consacre a la correspondance de Poincare avec des physiciens, le troisieme a celle avec des mathematiciens et le dernier aux echanges administratifs et prives de Poincare.

During his lifetime, Henri Poincare published three major philosophical books which achieved great success: "La science et l'hypothese" (1902), "La valeur de la science" (1905) and "Science et methode" (1908). After his death in 1913, a fourth volume of his philosophical works was published by his heirs as "Dernieres pensees" (1913). The four books constitute the core of Poincare's philosophic works and were given an ovation by scientific and general public. Around 1919, Gustave Le Bon wrote to Poincare's widow. As the director of the "Bibliotheque de Philosophie Scientifique at Flammarion,"...