The laboratory was in the same building as his observatory, in the Marais quarter of the town, a site occupied to-day by the Place des Vosges. Not far away is the Bastille, the magnificent Hôtel de Saint-Pol, and the brilliant Des Tournelles, the residence of the Kings before the Louvre was built. Here Louis XI had given his private physician, chancellor, and doctor of all the sciences, Coctier, a house which lay in a labyrinth-like park called the Garden of Daedalus. The doctor was speaking, and the expert listened: “Yes, Plato in his _Timaeus_ calls gold one of the densest and finest substances which filters through stone. There is a metal derived from gold which is black, and that is iron. But a substance more akin to gold is copper, which is composed of shining congealed fluids, and one of whose minor constituents is green earth. Now I ask, ‘Why cannot copper be freed from this last, and refined to gold?’” “Yes,” answered the expert, “it can, if one uses atramentum or the philosopher’s stone.” “What is that?” “Atramentum is copperas.” “Ventre-saint-gris! that is Plato’s iron! Now I see! Who taught you that?” “I learnt it from the greatest living magician in Wittenberg. His name is Dr. Faustus, and he has studied magic in Krakau.” “He is alive, then! Tell me! Tell me!” “This man, according to many witnesses, has done miracles like Christ; he has undertaken to restore the lost comedies of Plautus and Terence; his mind can soar on eagle’s wings and discover secrets of the heights and depths.” “Has he also found the elixir of life?” “Yes, since gold can be resolved into its elements.” “If gold can be resolved, then it has constituents. What are they?” “Gold can be easily dissolved in oil of vitriol, salts of ammonia, and saltpetre.” “What do you say?” The Doctor jumped up; the stove had heated the room and made him uncomfortable. “Let us go for a little walk,” he said; “but I must first make a note of what you say, for, when I wish to remember something important, the devil makes confusion in my head. These, then, are means of dissolving gold--oil of vitriol, salts of ammonia, and saltpetre!” The expert, whose name was Balthasar, now first noticed that he had given his information without obtaining a receipt or any equivalent for it, and, since he was not one of the unselfish kind, he threw out a feeler. “How is our gracious King?” The question revealed his secret and his wish, and put Doctor Coctier on his guard. “Ah,” he said to himself, “you have your eye on the King with your elixir of life.” And then he added aloud, “He is quite well.” “Oh! I had heard the opposite!” “Then they have lied.”