With regard to fermentation, too, Bernard was for many years in close accord with Pasteur, who taught that fermentation was the result of the chemical activity of living cells, the ferments. Toward the end of his life Bernard came to the view, however, that the action of ferments was really due to the presence in them of chemically active substances called diastases. These substances are of varied chemical {288} composition, but each one has a constant formula. Their presence in a fermentescible solution is sufficient of itself, even in the absence of living cells, to bring about fermentation. It has since been shown that after this substance is removed from ferment-cells by pressure, and the liquid carefully filtered so that absolutely no cells remain, fermentation will yet take place. This does not disprove the necessity for life to produce the diastases originally, though it advances science a step beyond the theory that it is the actual vital interchange of nutritious substances within the ferment-cell that causes fermentation. With each step of advance in biological science the mystery of life and its processes deepens. No one has done more to bring out the depths there are in vital function than Bernard. His early training was of the type that is, according to many prominent educators of our day, least calculated to develop originality of view, or capacity for initiating new lines of thought. Our pedagogic Solons would claim that the narrow orthodoxy that wrapped itself around his developmental years must surely stifle the precious genius for investigation that was in him. It is due, on the contrary, very probably to the thorough conservatism of his early training and the rounded fulness of the mental development acquired under the old system of classical education, that we have to chronicle of Bernard none of the errors by exaggeration of personal bias that are so common among even great scientific men. Few successful men have ever owed less to luck or to favoring circumstances in life. He was in the best sense a self-made man, and he owed his success to a large liberality of mind that enabled him to grasp things in their true proportions. With an imaginative faculty that constantly outstripped his experimental observations he was singularly free from prejudgment and was able to {289} control his theories by what he found, never allowing them to warp his powers of observation. Bernard is without doubt the greatest example of the century that a fully rounded youthful training is much more favorable to successful investigation than the early specialization which is falsely supposed to foster it. {290} {291} PASTEUR, FATHER OF PREVENTIVE MEDICINE {292}