In a previous chapter we spoke particularly of Roger Bacon's attitude toward the physical sciences, above all in what concerns the experimental method. He was typically modern in the standpoint that he assumed, as the only one by which knowledge of the things of nature can be obtained. It will be interesting now to see the number of things which Friar Bacon succeeded in discovering by the application of the principle of testing everything by personal observation, of not accepting things on second-hand authorities, and of not being afraid to say, "I do not know," in trying to learn for himself. His discoveries will seem almost incredible to a modern student of science and of education who has known nothing before of the progress of science made {322} by this wonderful man, or who has known only vaguely that Friar Bacon was a great original thinker in science, in spite of the fact that his life-history is bounded by the thirteenth century. I may say that the material of what I have to say of him, and also of his great contemporaries, Albertus Magnus and St. Thomas Aquinas, is taken almost literally from the chapter of my book, The Thirteenth Greatest of Centuries, on What They Studied at the Universities. Roger Bacon has been declared to be the discoverer of gunpowder, but this is a mistake, since it was known many years before by the Arabs and by them introduced into Europe. He did study explosives very deeply, however, and besides learning many things about them, realized how much might be accomplished by their use in the after-time. He declares in his Opus Magnum: "That one may cause to burst forth from bronze, thunderbolts more formidable that those produced by nature. A small quantity of prepared matter occasions a terrible explosion accompanied by a brilliant light. One may multiply this phenomenon so far as to destroy a city or an army." Considering how little was know about gunpowder at this time, this was of itself a marvelous anticipation of what might be accomplished by it.