In the midst of all this preoccupation of mind with science and all the scientific problems that were working in men's minds in his time, from the constitution of matter to the nature of life, above all engaged in experimental work, he was a deeply religious man in his opinions and practices. He had indeed the simple piety of a child. During the awful period of the French Revolution, he had some doubts with regard to religious truths; but once these were dispelled, he became one of the most faithful practical Catholics of his generation. He seldom passed a day without finding his way into a church, and his favorite form of prayer was the rosary. Frederick Ozanam tells the story of how he himself, overtaken by misgivings with regard to faith, and roaming almost aimlessly through the streets of Paris trying to think out solutions for his doubts, and the problems that would so insistently present themselves respecting the intellectual foundations of Christianity, finally wandered one day into a church, and found Ampère there in an obscure corner, telling his beads. Ozanam himself was moved to do the same thing, for Ampère was then looked upon as one of the greatest living scientists of France. Under the magic touch of an example like this and the quiet influence of prayer, Ozanam's doubts vanished, never to return. Saint-Beuve, whose testimony in a matter like this would surely be unsuspected of any tendency to make Ampère more Catholic than he was, in his introduction to Ampère's essay on the Philosophy of the Sciences (Paris, 1843), says: "The religious struggles and doubts of his earlier life had ceased. What disturbed him now lay in less exalted regions. Years ago, his interior conflicts, his instinctive yearning for the Eternal, and a lively correspondence with his old friend, Father Barrett, combined with the general tendency of the time of the Restoration, had led him back to that faith and devotion which he expressed so strikingly in 1803.... During the years which followed, up to the time of his death, we were filled with wonder and admiration at the way in which, without effort, he united religion and science; faith and confidence in the intellectual possibilities of man with adoring submission to the revealed word of God."