The father of modern rationalism, soldier of fortune, scholar, pilgrim, traveler, and firm adherent of the Roman Catholic faith. His philosophical work, which has often been summed up in his words, J pense, donc je suis (Cogito ergo sum), "I think, therefore I am," was given significant impulse by a dream he had on November 10, 1619. This revealed to him the method of philosophical speculation he was to follow, and his subsequent work is said to have stemmed from this experience.