Of course this is what might be expected. Anyone who reads the Papal decree can see at once that it has nothing to do with, or say about, chemistry or chemical investigation. Since, however, an aspersion has been cast upon the progress of chemistry during the Middle Ages, and since it will surely be thought by many people that, if chemistry did not happen to interest mankind at that time, it must have been because the Pope was opposed to it (for such seems to be the curious chain of reasoning of certain scholars), it has seemed well to review briefly the story of chemistry during the thirteenth, fourteenth and fifteenth centuries. More will be said about it in the chapter on Science at the Medieval Universities, and here the only idea is to bring out the fact that men were interested in what we now call chemical problems; that whatever interest they had was absolutely unhampered by ecclesiastical opposition; that indeed the very men who did the best work in this line, and their work is by no means without significance in the history of science, were all clergymen; and that most of them were in high favor with the Popes, and some of them have since received the honor of being canonized as saints. Take for a moment the example of the great English medieval scientist who wrote near the end of the {134} thirteenth century a work on science, which was undertaken at the command of the Pope of his time, to show him the character of the teaching of science at the University of Oxford. Roger Bacon defined the limits of chemistry very accurately and showed that he understood exactly what the subject and methods of investigation must be, in order that advance should be made in it. Of chemistry he speaks in his "Opus Tertium" in the following words: "There is a science which treats of the generation of things from their elements and of all inanimate things, as of the elements and liquids, simple and compound, common stones, gems and marble, gold and other metals, sulphur, salts, pigments, lapis lazuli, minium and other colors, oils, bitumen, and infinite more of which we find nothing in the books of Aristotle; nor are the natural philosophers nor any of the Latins acquainted with these things."