Lieutenant of police Gabriel Nicolas de la Reynie was the mainspring of the proceedings against the poisoners. He alone carried through the vast operations, bristling with difficulties. And it would be impossible to find any point of his administration in which his genius and his character appear in a more striking or complete manner. It is thanks to him, and to the careful notes he took daily on the cases of the prisoners, that we have been able to discover the facts of which Louis XIV believed he had destroyed every trace when he ordered the burning of the various documents in his private room. Saint-Simon, who has utterly shattered reputations which seemed firm as rock, pauses with respect before Nicolas de la Reynie, though the functions with which he was endowed were a subject of genuine abhorrence to him. 'La Reynie, councillor of state,' he writes, 'so well known for having been the first to lift the office of lieutenant of police from its natural low estate, and for making it a sort of ministerial office; a man of great importance too, because of the king's direct confidence in him, his constant relations with the Court, and the number of things in which he is concerned, and in which he has infinite powers of serving or harming in innumerable ways people of the greatest importance, obtained at length in 1697, at the age of eighty, permission to resign so arduous an employment, which he had for the first time ennobled by the equity, moderation, and disinterestedness with which he had fulfilled it, without swerving from the greatest scrupulousness, and doing the least possible injury as seldom as possible; he was, moreover, a man of great virtue and capacity, who in an office which he had, so to speak, created, and in which he was bound to draw upon him the hatred of the public, nevertheless won universal esteem.' We have a portrait of La Reynie by his friend Mignard, and an admirable etching of the painting by Van Schuppen. Engraving has never reproduced human features with more clearness, colour, and lifelikeness. The face bespeaks a clear, powerful, and well-balanced intelligence; the eyes express a firm and thoughtful kindliness. Such was the La Reynie who investigated the great poison cases. Though Bazin de Bezons of the French Academy had been associated with him in the Chambre Ardente as examining commissioner, it was the lieutenant of police who did all the work. The number of depositions, interrogatories, confrontations, pleadings, and other documents which he collected is enormous; and we see the magistrate with sure hand cutting a way through this tangled forest, guided by his experience, his knowledge of the human soul, and his clear intellect.