Thirdly, the marvelous maritime discoveries of new routes to India and of a new world, which revolutionized European commerce, added much to geographical knowledge and led to the construction of scientific maps of the earth's surface. Fourthly, the painstaking study of a small group of scholars afforded us our first glimpse of the real character of the vast universe about our own globe--the scientific basis of modern astronomy. Lastly, two profound thinkers, early in the seventeenth century,--Francis Bacon and Descartes,--pointed out new ways of using the reason--the method of modern science. In an earlier chapter, an account has been given of the maritime discoveries of the sixteenth century and their immediate results in broadening intellectual interests. In this chapter, some attention already has been devoted to the rise of humanism and likewise to the invention of printing. It remains, therefore, to say a few words about the changes in astronomy and in scientific method that characterized the beginning of modern times. [Side Note: Astronomy] In the year 1500 the average European knew something about the universe of sun, moon, planets, and stars, but it was scarcely more than the ancient Greeks had known, and its chief use was to foretell the future. This practical aspect of astronomy was a curious ancient misconception, which now passes under the name of astrology. It was popularly believed prior to the sixteenth century that every heavenly body exerted a direct and arbitrary influence upon human character and events, [Footnote: Disease was attributed to planetary influence. This connection between medicine and astrology survives in the sign of Jupiter 4, which still heads medicinal prescriptions.] and that by casting "horoscopes," showing just how the stars appeared at the birth of any person, the subsequent career of such an one might be foreseen. Many silly notions and superstitions grew up about astrology, yet the practice persisted. Charles V and Francis I, great rivals in war, vied with each other in securing the services of most eminent astrologers, and Catherine de' Medici never tired of reading horoscopes. [Sidenote: "The Ptolemaic System"]