Astrology in medieval Islam in the context of "Astrologer"

Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that propose that information about human affairs and terrestrial events may be discerned by studying the apparent positions of celestial objects. Different cultures have employed forms of astrology since at least the 2nd millennium BCE, these practices having originated in calendrical systems used to predict seasonal shifts and to interpret celestial cycles as signs of divine communications.

Most, if not all, cultures have attached importance to what they observed in the sky, and some—such as the Hindus, Chinese, and the Maya—developed elaborate systems for predicting terrestrial events from celestial observations. Western astrology, one of the oldest astrological systems still in use, can trace its roots to 19th–17th century BCE Mesopotamia, from where it spread to Ancient Greece, Rome, the Islamic world, and eventually Central and Western Europe. Contemporary Western astrology is often associated with systems of horoscopes that purport to explain aspects of a person's personality and predict significant events in their lives based on the positions of celestial objects; the majority of professional astrologers rely on such systems.

Abū Mūsā Jābir ibn Ḥayyān (Arabic: أَبو موسى جابِر بِن حَيّان, variously called al-Ṣūfī, al-Azdī, al-Kūfī, or al-Ṭūsī), died c. 806−816, is the purported author of a large number of works in Arabic, often called the Jabirian corpus. The c. 215 treatises that survive today mainly deal with alchemy and chemistry, magic, and Shi'ite religious philosophy. However, the original scope of the corpus was vast, covering a wide range of topics ranging from cosmology, astronomy and astrology, over medicine, pharmacology, zoology and botany, to metaphysics, logic, and grammar.

The works attributed to Jabir, which are tentatively dated to c. 850 – c. 950, contain the oldest known systematic classification of chemical substances, and the oldest known instructions for deriving an inorganic compound (sal ammoniac or ammonium chloride) from organic substances (such as plants, blood, and hair) by chemical means. His works also contain one of the earliest known versions of the sulfur-mercury theory of metals, a mineralogical theory that would remain dominant until the 18th century.