The return to Sèvres, which he greatly liked, was to him a daily source of pleasure. I can see him now, hastily coming out of the train, his pockets full of papers and brochures which he read in the train and parcels in his hands, for he loved to bring home little presents. A kindly smile illumined his face and he never failed to express the pleasure he felt at coming home. "How pure the air is! How green the grass! What peace! You see, if I did not go to Paris to work I should not be so alive to the charm of Sèvres and the pleasure of rest." He used to come home at seven and do no more work; it was his daily rest. He then gave himself up to complete relaxation, joked, related the incidents of the day, spoke of his researches, planned experiments for the next day, read aloud part of the evening and then listened to music, not only because he liked it, but also because he wanted to "switch on to another line," _i.e._ rest his mind completely. He was an incomparable companion, always alive and communicative, generously giving out the treasures of his heart and his intelligence. He liked a simple life; all artifice, all convention displeased him. He disliked luxury in his person to that extent that he never consented to possess a gold watch nor any object with no particular use. His only luxury was to gratify others. He enjoyed peaceful family life and a circle of intimate friends. Yet, appreciating as he did all serious manifestations of life, he was glad to have the opportunity of meeting people who were interesting either in themselves or for the knowledge which they could impart. In Life as in Science he found precepts to help the evolution of his moral and philosophical ideas, which he placed in their turn at Life's service. If he could not solve a problem, he at least pointed out its importance. His attentive penetration of things in themselves, coupled with a creative imagination, was the force which enabled him to open out new prospects and new paths. On looking back upon his own life, he used to say that the period spent at the Pasteur Institute had been the happiest, the most favourable to his scientific work; he therefore remained deeply attached to it until the end of his life. CHAPTER XXIII Opposition to the phagocyte theory--Scientific controversies --Experiments in support of the phagocyte theory--Behring and antitoxins--The London Congress--Inflammation. As long as Metchnikoff was but a zoologist, the scientific atmosphere around him remained calm and serene. But everything changed suddenly when he entered the domain of pathology with his theory of phagocytes and phagocytosis.