The old priest, whose heart was so ingenuous, and who knew nothing of love and passion, was nevertheless the only one who had understood the truth.

He had told Pierre that he was changed, that there was another man in him.

And he, Pierre, had foolishly and stubbornly declared that he was the same as he had always been; whereas Marie had already transformed him, bringing all nature back to his breast--all nature, with its sunlit countrysides, its fructifying breezes, and its vast heavens, whose glow ripens its crops.

That indeed was why he had felt so exasperated with Catholicism, that religion of death; that was why he had shouted that the Gospel was useless, and that the world awaited another law--a law of terrestrial happiness, human justice and living love and fruitfulness! Ah, but Guillaume?
Then a vision of his brother rose before Pierre, that brother who loved him so fondly, and who had carried him to his home of toil, quietude and affection, in order to cure him of his sufferings.

If he knew Marie it was simply because Guillaume had chosen that he should know her.