With Pasteur to conceive an idea was to think out its experimental demonstration. He manufactured the paratartrates according to the directions given by Mitscherlich, and then proceeded to sort the two varieties of crystals by hand. It was slow, patient work, and for hours Pasteur strove feverishly on alone in the laboratory. At length, the crystals were ready for solution and examination as to their effect upon polarized light. If Pasteur's idea as to the dissymmetry of crystals were confirmed, a great scientific advance was assured. Tremblingly the young enthusiast adjusted his polariscope. He tells the story himself of his first hesitant glance. But hesitation was changed to triumph. His prevision was correct. There were two forms of crystals with different effects on polarized light in Mitscherlich's supposed simple substance. Pasteur could not stay to put his instrument away. The air of the laboratory had become oppressive to him. Drunk with the wine of discovery, as a French biographer remarks, he rushed into the open air and almost staggered into the arms of a friend who was passing. "Ah," he said, "I have just made a great discovery. Come to the Luxembourg garden and I will tell you all about {299} it." It was characteristic of the man all through life to have no doubt of the true significance of his work. He was sure of each step in the demonstration and his conclusions were beyond doubt. Pasteur's discovery made a profound sensation. The French Academy of Sciences at once proceeded to its investigation. Among the members who were intensely interested, some bore names that now belong to universal science--Arago, Biot, Dumas, De Senarmont. Pasteur told long years afterward of Biot's emotion when the facts were visibly demonstrated to him. Greatly moved, the distinguished old man took the young man's arm and, trembling, said: "My dear child, I have loved science so well that this makes my heart beat." How deeply these men were bound up in their work! How richly they were rewarded for their devotion to science! There were giants in those days.