He said nothing; he began to doubt whether he had really seen his chief at Saint-Sulpice. Desplein would not have troubled himself to tell Bianchon a lie, they knew each other too well; they had already exchanged thoughts on quite equally serious subjects, and discussed systems de natura rerum, probing or dissecting them with the knife and scalpel of incredulity. Three months went by. Bianchon did not attempt to follow the matter up, though it remained stamped on his memory. One day that year, one of the physicians of the Hotel-Dieu took Desplein by the arm, as if to question him, in Bianchon's presence. "What were you doing at Saint-Sulpice, my dear master?" said he. "I went to see a priest who has a diseased knee-bone, and to whom the Duchesse d'Angouleme did me the honor to recommend me," said Desplein. The questioner took this defeat for an answer; not so Bianchon. "Oh, he goes to see damaged knees in church!--He went to mass," said the young man to himself. Bianchon resolved to watch Desplein. He remembered the day and hour when he had detected him going into Saint-Sulpice, and resolved to be there again next year on the same day and at the same hour, to see if he should find him there again. In that case the periodicity of his devotion would justify a scientific investigation; for in such a man there ought to be no direct antagonism of thought and action. Next year, on the said day and hour, Bianchon, who had already ceased to be Desplein's house surgeon, saw the great man's cab standing at the corner of the Rue de Tournon and the Rue du Petit-Lion, whence his friend jesuitically crept along by the wall of Saint-Sulpice, and once more attended mass in front of the Virgin's altar. It was Desplein, sure enough! The master-surgeon, the atheist at heart, the worshiper by chance. The mystery was greater than ever; the regularity of the phenomenon complicated it. When Desplein had left, Bianchon went to the sacristan, who took charge of the chapel, and asked him whether the gentleman were a constant worshiper. "For twenty years that I have been here," replied the man, "M. Desplein has come four times a year to attend this mass. He founded it." "A mass founded by him!" said Bianchon, as he went away. "This is as great a mystery as the Immaculate Conception--an article which alone is enough to make a physician an unbeliever."