However, astrology has not always ruled our kind with equal strength. There were periods during which belief in the fate-determining power of the stars was more dominant, and others in which it was feebler. The ancient world, which was blindly devoted to all kinds of superstition, had also cherished and fostered astrology. But when the ancient theory of life was demolished later on, and the Christian God of love had taken possession of the world, the belief in the fate-determining power of the stars was shaken, and centuries, followed during which _Medicina Astrologica_, altho it did not by any means disappear entirely, was forced more or less to the rear. Astrology did not become resurrected until scholasticism and dogmatism had held back the activity of the mind from independent investigation, thus bringing about the intellectual darkness which for centuries prevailed. This use of astrology truly forms one of the most wonderful pages in the history of the development of our race, for an actual _furor astrologicus_ seized upon the world in the course of the thirteenth century. The movement originated at the court of Emperor Frederick II. The great Ghibelline was so positive and so enthusiastic an adherent of all astrologic doctrines that he did not decide upon any undertaking until he had first learned the opinion of the stars regarding his enterprise. It was his firm belief that the stars prophesied for him a political rôle which was to shake the entire world, and of his astrological prediction he apprised his adversary, the pope, in the following words: Fata volunt, stellaeque docent, animumque volatus, Quod Fridericus ego malleus orbis ero.