550 Outlines of European Histoty Discoveries of the thirteenth century peculiarities of a single fly and give the reason for its color and why it has just so many feet, no more and no less." Bacon held that truth could be reached a hundred thousand times better by experiments with real things than by poring over the bad Latin translations of Aristotle. " If I had my way," he declared, " I should burn all the books of Aristotle, for the study of them can only lead to a loss of time, produce error and increase ignorance." Roger Bacon declared that if men would only study common things instead of reading the books of the ancients, science would outdo the wonders which people of his day thought could be produced by magic. He said that in time men would be able to fly, would have carriages which needed no horses to draw them and ships which would move swiftly without oars, and that bridges could be built without piers to support them. All this and much more has come true, but inventors and modern scientists owe but little to the books of the Greeks and Romans, which the scholastic philosophers and the Humanists relied upon. Although the Greek philosophers devoted consider- able attention to natural science, they were not much inclined to make long and careful experiments or to invent anything like the microscope or telescope to help them. They knew very litde indeed about the laws of nature and were sadly mistaken upon many points. Aristotle thought that the sun and all the stars revolved about the earth and that the heavenly bodies were per- fect and unchangeable. He believed that heavy bodies fell faster than light ones and that all earthly things were made -of the four elements — earth, air, water, and fire. The Greeks and Romans knew nothing of the compass, or gunpowder, or the printing press, or the uses to which steam can be put. Indeed, they had scarcely anything that we should call a machine. The thirteenth century witnessed certain absolutely new achievements in the history of mankind. The compass began to be utilized in a way to encourage bolder and bolder ventures out upon the ocean (see above, section 91). The properties of the lens were discovered, and before the end of the century
