A man of much greater interest to us from the medical point of view is Roger Bacon and for two reasons. More than any other mediaeval mind he saw the need of the study of nature by a new method. The man who could write such a sentence as this: "Experimental science has three great prerogatives over other sciences; it verifies conclusions by direct experiment; it discovers truth which they never otherwise would reach; it investigates the course of nature and opens to us a knowledge of the past and of the future," is mentally of our day and generation. Bacon was born out of due time, and his contemporaries had little sympathy with his philosophy, and still less with his mechanical schemes and inventions. From the days of the Greeks, no one had had so keen an appreciation of what experiment meant in the development of human knowledge, and he was obsessed with the idea, so commonplace to us, that knowledge should have its utility and its practical bearing. "His chief merit is that he was one of the first to point the way to original research--as opposed to the acceptance of an authority--though he himself still lacked the means of pursuing this path consistently. His inability to satisfy this impulse led to a sort of longing, which is expressed in the numerous passages in his works where he anticipates man's greater mastery over nature."(23) (23) Dannemann: Die Naturwissenschaften in ihrer Entwicklung und in ibrem Zusammenhange, Leipzig, 1910, Vol. I, pp. 278-279. Bacon wrote a number of medical treatises, most of which remain in manuscript. His treatise on the "Cure of Old Age and the Preservation of Youth" was printed in English in 1683.(24) His authorities were largely Arabian. One of his manuscripts is "On the Bad Practices of Physicians." On June 10, 1914, the eve of his birth, the septencentenary of Roger Bacon will be celebrated by Oxford, the university of which he is the most distinguished ornament. His unpublished MSS. in the Bodleian will be issued by the Clarendon Press (1915-1920), and it is hoped that his unpublished medical writings will be included. (24) It may be interesting to note the three causes to which he attributes old age: "As the World waxeth old, Men grow old with it: not by reason of the Age of the World, but because of the great Increase of living Creatures, which infect the very Air, that every way encompasseth us, and Through our Negligence in ordering our Lives, and That great Ignorance of the Properties which are in things conducing to Health, which might help a disordered way of Living, and might supply the defect of due Government."