Astrology (Gr. star or constellation, and discourse), a system of rules for discovering future events by studying the positions of the heavenly bodies, which was received for ages as a science, but has now lost all credit in civilized nations. It was divided into two kinds: judicial, by which the fate and acts of men and nations might be foreknown; and natural, by which the events of brute and inanimate nature, such as the changes of the weather, etc, might be predicted. The etymological meaning of the word astrology is almost the same as that of astronomy; and there was no clear distinction made between the two branches until the time of Galileo. Previously, most students of the movements of the heavenly bodies had been more or less astrologers. The invention of the telescope and the general establishment of the Copernican system first gradually displaced astrology for the benefit of true scientific knowledge. - Astrology was early developed in Egypt, but chiefly flourished in Chaldea, whose "star-gazers and monthly prognosticators " were so famous that the name Chaldee came to be used as identical with astrologer, not only in the Scriptures, but also by the classical writers. In the East it still has its votaries.
It was much practised in imperial Rome. It was forbidden by Augustus, and the edict was often reenacted by later emperors, but was apparently not much regarded. The Arabs revived astrology with astronomy. The Moors in Spain held it in great respect, and by their influence it was made popular among the Gothic nations of western Europe. The astronomical tables of Alfonso X. in the 13th century were in great part intended for astrological purposes. Astrology continued to increase in credit till the middle of the 10th century, was still practised at European courts at the end of the 17th, and had a few votaries till the end of the 18th, even in England. It was in high repute at the court of Catharine de' Medici; it was considered a science even by Kepler; and Lilly, the last of the famous astrologers, was called before a committee of the house of commons in the reign of Charles II. to give his opinion of future events. - The general method of procedure in finding the fate of any man or enterprise was to draw a horoscope, representing the position of the stars and planets, either in the whole heaven, or within one degree above the eastern horizon, at the time of birth of the individual or the inception of the undertaking.
Arbitrary significations were given to different heavenly bodies, as they appeared singly or in conjunction; and according to these significations, the horoscope was interpreted. The presence of Venus foretold love; Mars, war; Jupiter, power; the Pleiades, storms at sea, etc. The system of a reputable astrologer in the 16th century required years for its mastery; and absurd as its fundamental principles now appear, its details were not inconsistent with each other, and the whole system has a completeness which appears very singular in a scheme so visionary.