And you may guess how Pasteur was worried! This was no affair like anthrax, where, if the vaccine was a little, just a shade too strong, a few sheep would die. Here a slip meant the lives of babies.... Never was any microbe hunter faced with a worse riddle. “Not a single one of all my dogs has ever died from the vaccine,” Pasteur pondered. “All of the bitten ones have been perfectly protected by it.... It must work the same way on humans--it _must_ ... but....” And then sleep once more was not to be had by this poor searcher who had made a too wonderful discovery.... Horrid pictures of babies crying for the water their strangled throats would not let them drink--children killed by his own hands--such visions floated before him in the dark.... For a moment the actor, the maker of grand theatric gestures, rose in him again: “I am much inclined to begin on myself--inoculating myself with rabies, and then arresting the consequences; for I am beginning to feel very sure of my results,” he wrote to his old friend, Jules Vercel. At last, mercifully, the worried Mrs. Meister from Meissengott in Alsace took the dreadful decision out of Pasteur’s unsure hands. This woman came crying into the laboratory, leading her nine-year-old boy, Joseph, gashed in fourteen places two days before by a mad dog. He was a pitifully whimpering, scared boy--hardly able to walk. “Save my little boy--Mr. Pasteur,” this woman begged him. Pasteur told the woman to come back at five in the evening, and meanwhile he went to see the two physicians, Vulpian and Grancher--admirers who had been in his laboratory, who had seen the perfect way in which Pasteur could guard dogs from rabies after they had been terribly bitten. That evening they went with him to see the boy, and when Vulpian saw the angry festering wounds he urged Pasteur to start his inoculations: “Go ahead,” said Vulpian, “if you do nothing it is almost sure that he will die.” And that night of July 6, 1885, they made the first injection of the weakened microbes of hydrophobia into a human being. Then, day after day, the boy Meister went without a hitch through his fourteen injections--which were only slight pricks of the hypodermic needle into his skin. And the boy went home to Alsace and had never a sign of that dreadful disease. Then all fears left Pasteur--it was very much like the case of that first dog that Roux had injected years before, against the master’s wishes. So it was now with human beings; once little Meister came through unhurt, Pasteur shouted to the world that he was prepared to guard the people of the world from hydrophobia. This one case had completely chased his fears, his doubts--those vivid but not very deep-lying doubts of the artist that was in Louis Pasteur.