Ptolemy among his good services did one ill to mankind by his _Tetrabiblon_ or “Quadripertit,” an astrological treatise which was current with the Almagest in the Western Schools. This authoritative treatise, together with the Aristotelian conception of the heavens, gave to astrology the aspect of a regular science with its own principles and methods; a science admired and even courted by princes. As Frederick the Second and Charles the Fifth would learn of the stars the moment to take the field against their foes, so the medieval physician sought their countenance in the letting of blood or in the exhibition of a clyster or emetic. The Church, abhorring all concurrent dominion, and justly abhorring this bondage of the judgment of God and of the will of man, almost alone withstood the astrologer. If the doctors of theology did not know how to deny the power of the stars in the material cosmos, they vehemently denied it in the world of the spirit. “Et ideo pro certo tenendum est,” says Aquinas, “grave peccatum esse circa ea quæ a voluntate hominis dependent judiciis astrorum uti.” Of the priestly assailants of astrology, the most attractive to us for his wit, sagacity and sound knowledge, was Nicholas Oresme, sometime Bishop of Lisieux (died 1382), translator of the _Ethics_ and other Aristotelian treatises, as he is portrayed for us by Hauréau (_Dict. des Sciences philosophiques_, art. Oresme) and M. Charles Jourdain. The fun of the thing is that the outspoken Oresme was the counsellor, the friend, and even the tutor of that notable astrologer Charles the Fifth; a story as honourable to the prince as to the subject. As Charles issued from the chambers of his astrologers the discourses of Oresme must have made him a little uncomfortable, especially when Oresme records the misfortunes of astrologising captains, such as Alphonso king of Castille, of whom, says he, I have heard nothing notable except that he cast horoscopes, was unfortunate in war, and neglected his kingdom; or such again as James the king of Majorca, a passionate astrologer, who on the dictation of the stars made a sortie against Peter of Aragon, and never came back again. It is all very well, says Oresme, for kings to know somewhat of the noble science of astronomy, but they must be content to hear of it in talk with sages, and not to spend upon the stars time and care which they should devote to the interests of their people. “Mesmement tele chose (astrology, necromancy, geomancy and “quelconques tels ars”) est plus périlleuse à personnes d’estat, comme sont princes et seigneurs ausquelz appartient le gouvernement publique. Et pour ce ay je composé ce livret en françois afin que gens lais le puissent entendre, desquels, si comme j’ay entendu, plusieurs sont trop enclins à telles fatuités. Et autres fois ay je escript en latin de ceste matière” etc. In spite of the Bishop of Lisieux, astrology at the end of the fourteenth century