Pasteur at first declined this offer. It was at the moment when the results of his investigations on organised ferments opened to him a wide career; it was at the time when, as an application of his latest studies, he had just recognised the true theory of the fabrication of vinegar, and had discovered the cause of the diseases of wines; it was, in short, at the moment when, after having thrown light upon the question of spontaneous generation, the infinitely little appeared infinitely great. He saw living ferments present everywhere, whether as agents of decomposition employed to render back to the atmosphere all that had lived, or as direct authors of contagious maladies. And now it was proposed to him to quit this path, where his footing was sure, which offered him an unlimited horizon in all directions, to enter on an unknown road, perhaps without an outlet. Might he not expose himself to the loss of months, perhaps of years, in barren efforts? M. Dumas insisted. 'I attach,' said he to his old pupil, now become his colleague and his friend, 'an extreme value to your fixing your attention upon the question which interests my poor country. Its misery is beyond anything that you can imagine.' 'But consider,' said Pasteur, 'that I have never handled a silkworm.' 'So much the better,' replied M. Dumas. 'If you know nothing about the subject, you will have no other ideas than those which come to you from your own observations.' Pasteur allowed himself to be persuaded, less by the force of these arguments than by the desire to give his illustrious master a proof of his profound deference. * * * * * As soon as the promise was given and the resolution made to go to the South, Pasteur thought over the method to be employed in the pursuit of the problem. Certainly, amidst the labyrinth of facts and opinions, it was not hypotheses which were wanting. For seventeen years they had been rising up on all sides.