For a time Sainte-Croix hesitated: at last he yielded to the taunts of his companion, who accused Frenchmen of showing too much honour in their crimes, of allowing themselves to be involved in the ruin of their enemies, whereas they might easily survive them and triumph over their destruction. In opposition to this French gallantry, which often involves the murderer in a death more cruel than that he has given, he pointed to the Florentine traitor with his amiable smile and his deadly poison. He indicated certain powders and potions, some of them of dull action, wearing out the victim so slowly that he dies after long suffering; others violent and so quick, that they kill like a flash of lightning, leaving not even time for a single cry. Little by little Sainte-Croix became interested in the ghastly science that puts the lives of all men in the hand of one. He joined in Exili’s experiments; then he grew clever enough to make them for himself; and when, at the year’s end, he left the Bastille, the pupil was almost as accomplished as his master. Sainte-Croix returned into that society which had banished him, fortified by a fatal secret by whose aid he could repay all the evil he had received. Soon afterwards Exili was set free—how it happened is not known—and sought out Sainte-Croix, who let him a room in the name of his steward, Martin de Breuille, a room situated in the blind, alley off the Place Maubert, owned by a woman called Brunet. It is not known whether Sainte-Croix had an opportunity of seeing the Marquise de Brinvilliers during his sojourn in the Bastille, but it is certain that as soon as he was a free man the lovers were more attached than ever. They had learned by experience, however, of what they had to fear; so they resolved that they would at once make trial of Sainte-Croix’s newly acquired knowledge, and M. d’Aubray was selected by his daughter for the first victim. At one blow she would free herself from the inconvenience of his rigid censorship, and by inheriting his goods would repair her own fortune, which had been almost dissipated by her husband. But in trying such a bold stroke one must be very sure of results, so the marquise decided to experiment beforehand on another person. Accordingly, when one day after luncheon her maid, Francoise Roussel, came into her room, she gave her a slice of mutton and some preserved gooseberries for her own meal. The girl unsuspiciously ate what her mistress gave her, but almost at once felt ill, saying she had severe pain in the stomach, and a sensation as though her heart were being pricked with pins. But she did not die, and the marquise perceived that the poison needed to be made stronger, and returned it to Sainte-Croix, who brought her some more in a few days’ time.