Descartes was personally a believer, a sincere Catholic. His education by the Jesuits of La Flèche, and the philosophy they had taught him there, had marked him profoundly. This man, whose mind is so free and enquiring, who was always so conscious of a vitally important intellectual vocation, who grounded all his philosophy on a daring effort to doubt everything, that he might vanquish doubt by doubt and is discover the unimpeachable certainties implied in the very existence of the thinking self, this founder of modern rationalism never doubted the Catholic creed; he could even be blamed for being insufficiently aware of that anxious questing restlessness of the soul that is worked upon and deepened by Faith. To the Protestant theologians who tried to force the religious issue on him, he answered smiling that he preferred to remain in the religion of his king and his nurse.

He was not giving them his reasons for believing; he meant merely that he preferred to be left in peace on this matter. His death was nobly and genuinely Christian. That fine sense he always had of the dignity of reason and intellectual integrity, of the grandeur of created nature, was itself religious. I am sure that at the opening of his philosophical career, with the illuminative experience of November 10th, 1619, still vivid within him, he was equally desirous of establishing the principles of physical geometry—his work par excellence— and of grounding Christian doctrine on such firm foundations that atheists and sceptics would be silenced for ever. And with all this his hostility to Theology was stubborn and bitter and calculating. How explain this paradox?