The Empress had been much interested, and wished that her five o’clock friends--who were waiting in the room where tea was served--should also acquire some notions of these studies. She merrily took up the microscope, laughing at her new occupation of laboratory attendant, and arrived thus laden in the drawing-room, much to the surprise of her privileged guests. Pasteur came in behind her, and gave a short and simple account of a few general ideas and precise discoveries. In the same way, the preceding week, Le Verrier[25] had spoken of his planet, and Dr. Longet had given a lecture on the circulation of the blood. That butterfly world of the Court, taking a momentary interest in scientific things, did not foresee that the smallest discovery made in the poor laboratory of the Rue d’Ulm would leave a more lasting impression than the fêtes of the Tuileries of Fontainebleau and of Compiègne. In the course of their private interview, Napoleon and Eugénie manifested some surprise that Pasteur should not endeavour to turn his discoveries and their applications to a source of legitimate profit. “In France,” he replied, “scientists would consider that they lowered themselves by doing so.” He was convinced that a man of pure science would complicate his life, the order of his thoughts, and risk paralysing his inventive faculties, if he were to make money by his discoveries. For instance, if he had followed up the industrial results of his studies on vinegar, his time would have been too much and too regularly occupied, and he would not have been free for new researches. “My mind is free,” he said. “I am as full of ardour for the new question of silkworm disease as I was in 1863, when I took up the wine question.” What he most wished was to be able to watch the growth of the silkworms from the very first day, and to pursue without interruption this serious study in which the future of France was interested. That, and the desire to have one day a laboratory adequate to the magnitude of his works were his only ambitions. On his return to Pam he obtained leave to go back to Alais. “My dear Raulin,” wrote Pasteur to his former pupil in January, 1866. “I am again entrusted by the Minister of Agriculture with a mission for the study of silkworm disease, which will last at least five months, from February 1 to the end of June. Would you care to join me?” Raulin excused himself; he was then preparing, with his accustomed slow conscientiousness, his doctor’s thesis, a work afterwards considered by competent judges to be a masterpiece. “I must console myself,” wrote Pasteur, expressing his regrets, “by thinking that you will complete your excellent thesis.”