“I have derived from them so great a satisfaction, and my admiration for his talent has been confirmed and increased to such an extent that I cannot resist the somewhat rash desire of communicating my impressions....” Amongst Claude Bernard’s discoveries, Pasteur chose that which seemed to him most instructive, and which Claude Bernard himself appreciated most: “When M. Bernard became in 1854 a candidate for the Académie des Sciences, his discovery of the glycogenic functions of the liver was neither the first nor the last among those which had already placed him so high in the estimation of men of science; yet it was by that one that he headed his list of the claims which could recommend him to the suffrages of the illustrious body. That preference on the part of the master decides me in mine.” Claude Bernard had begun by meditating deeply on the disease known as diabetes and which is characterized, as everybody knows, by a superabundance of sugar in the whole of the organism, the urine often being laden with it. But how is it, wondered Claude Bernard, that the quantity of sugar expelled by a diabetic patient can so far surpass that with which he is provided by the starchy or sugary substances which form part of his food? How is it that the presence of sugary matter in the blood and its expulsion through urine are never completely arrested, even when all sugary or starchy alimentation is suppressed? Are there in the human organism sugar-producing phenomena unknown to chemists and physiologists? All the notions of science were contrary to that mode of thinking; it was affirmed that the vegetable kingdom only could produce sugar, and it seemed an insane hypothesis to suppose that the animal organism could fabricate any. Claude Bernard dwelt upon it however, his principle in experimentation being this: “When you meet with a fact opposed to a prevailing theory, you should adhere to the fact and abandon the theory, even when the latter is supported by great authorities and generally adopted.” This is what he imagined, summed up in a few words by Pasteur--