It is generally thought that Roger Bacon, the famous monk of the thirteenth century, was a very great man and that he possessed true knowledge, because he was persecuted and condemned to prison by a set of ignoramuses. It is a great prejudice in his favor, I own. But does it not happen every day that quacks gravely condemn other quacks, and that fools make other fools pay the penalty of folly? This, our world, has for a long time resembled the compact edifices in which he who believes in the eternal Father anathematizes him who believes in the Holy Ghost; circumstances which are not very rare even in these days. Among the things which render Friar Bacon commendable we must first reckon his imprisonment, and then the noble boldness with which he declared that all the books of Aristotle were fit only to be burned and that at a time when the learned respected Aristotle much more than the Jansenists respect St. Augustine. Has Roger Bacon, however, done anything better than the Poetics, the Rhetoric, and the Logic of Aristotle? These three immortal works clearly prove that Aristotle was a very great and fine genius--penetrating, profound, and methodical; and that he was only a bad natural philosopher because it was impossible to penetrate into the depths of physical science without the aid of instruments. Does Roger Bacon, in his best work, in which he treats of light and vision, express himself much more clearly than Aristotle when he says light is created by means of multiplying its luminous species, which action is called univocal and conformable to the agent? He also mentions another equivocal multiplication, by which light engenders heat and heat putrefaction. Roger Bacon likewise tells us that life may be prolonged by means of spermaceti, aloes, and dragons' flesh, and that the philosopher's stone would render us immortal. It is thought that besides these fine secrets he possessed all those of judicial astrology, without exception, as he affirms very positively in his _"Opus Majus,"_ that the head of man is subject to the influences of the ram, his neck to those of the bull, and his arms to the power of the twins. He even demonstrates these fine things from experience, and highly praises a great astrologer at Paris who says that he hindered a surgeon from putting a plaster on the leg of an invalid, because the sun was then in the sign of Aquarius, and Aquarius is fatal to legs to which plasters are applied. It is an opinion quite generally received that Roger was the inventor of gunpowder. It is certain that it was in his time that important discovery was made, for I always remark that the spirit of invention is of all times and that the doctors, or sages, who govern both mind and body are generally profoundly ignorant, foolishly prejudiced, or at war with common sense. It is usually among obscure men that artists are found animated with a superior instinct, who invent admirable things on which the learned afterwards reason.