From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 356-357

Courtesy of

Fārābī: Abū Nar Muammad ibn Muammad ibn Tarkhān al‐Fārābī

Alnoor Dhanani

Alternate name


BornFārāb, (Turkmenistan), circa 870

DiedDamascus, (Syria), 950

Fārābī is mainly known as a philosopher, and his writings on the classification of the sciences, including astronomy and astrology, were influential both in the Islamic world and in Europe. Not much is known about Fārābī's early years. He studied logic with the Nestorian Christian Yuannā ibn aylān (died: circa 932) in Marw and then in Baghdad. In Baghdad, Fārābī studied Arabic and was therefore able to participate in the philosophical salons of Baghdad and to make use of Arabic philosophical and scientific works. He then went to Constantinople with his teacher during the reign of the ʿAbbāsid caliph al‐Muktafī (902–908) or early during the reign of Caliph al‐Muqtadir (908–932). He returned to Baghdad between 910 and 920, spending two decades there writing and teaching philosophy and allied sciences. In 942, Fārābī left Baghdad, probably to escape its instability, going first to Damascus and then to Egypt. He later returned to Damascus to join the court of the amdānid Prince Sayf al‐Dawla but died a year later.

Fārābī is known primarily for his contributions to Islamic philosophy; he was known as “The Second Teacher” (al‐muʿallim al‐thānī), the First Teacher being Aristotle. His works include commentaries on Aristotle and Plato; introductory philosophical works; treatises on logic, metaphysics, political philosophy; and other philosophical disciplines; a treatise on the classification of knowledge, and works in the mathematical sciences, which include astronomy and music.

In The Enumeration of the Sciences (Iḥṣāʾ al‐ʿulūm), Fārābī discusses the place of astronomy within the classification of knowledge, its subject matter, its demarcation from astrology, and its relationship with mathematics. He there classifies knowledge broadly into the major divisions of the linguistic sciences, logic, mathematics, physics, metaphysics, the civic sciences of ethics and political philosophy, law, and theology. Mathematics consists of seven branches: arithmetic, geometry, optics, astronomy, music, statics (i. e., “the science of weights”), and technology. Astronomy, or the “science of the stars” (ʿilm al‐nujūm), consists of two parts. The first is astrology (ʿilm akām al‐nujūm), which studies the signs of planets with regard to their relationship with future events, and sometimes also present and past events. The second part of astronomy is “mathematical astronomy” (ʿilm al‐nujūm al‐taʿlīmī), which, unlike astrology, is considered one of the mathematical sciences.

Mathematical astronomy investigates celestial bodies and the Earth with regard to their shapes, sizes, and distances; it investigates their motions, the components of these motions, the calculation of positions of planets as a result of these motions at any specific time, and the observable effects of motions, for example eclipses and planetary risings and settings. Furthermore, it investigates the inhabitable areas of the Earth, its climatic regions, and timekeeping, i. e., seasonal hours. The determination that the Earth is entirely at rest at the center of the Universe and that motions of celestial bodies are spherical is made by mathematical astronomy.

Fārābī's grounds for rejecting astrology are clear in two surviving works: On the Utility of the Sciences and the Crafts (Risāla fī faīlat al‐ʿulūm wa‐ʾl‐ināʿāt) and On the Aspects in which Belief in Astrology Is Valid (Maqāla fī al‐jihāt allatī taiḥḥu ʿalayhā al‐qawl bi‐akām al‐nujūm). Fārābī acknowledges that celestial bodies have an effect on terrestrial bodies, but he believes this effect to be mediated through the light radiated by the celestial bodies. There is also a chain of causes from a particular position of a planet to its eventual effect upon a particular terrestrial body. Therefore, one is not dealing with a direct and necessary cause‐and‐effect relationship between planetary position and an immediate terrestrial effect, but rather with the relationship between a cause and its possible far‐removed and remote effect. Any astrological prediction must take into account natural and voluntary obstacles that may prevent the occurrence of the eventual effect. Fārābī concludes that astrology is just conjecture, supposition, smooth talk, and deception.

Fārābī's philosophical cosmology was shaped by astronomy. He discusses the doctrine of the ten intellects in his On the Opinions of the Inhabitants of the Virtuous City (Kitāb arāʾ ahl al‐madīna al‐fāila). The First Intellect necessarily emanates from the First Being, namely God. Like the First Being, the First Intellect is immaterial. As it contemplates the First Being, the First Intellect necessarily brings a third being, namely the Second Intellect into existence. As it contemplates itself, the First Intellect necessarily brings the celestial heaven into existence. The Second Intellect also contemplates the First Being, which necessarily brings the Third Intellect into existence. The Second Intellect's contemplation of itself brings the sphere of fixed stars into existence. Similarly, the contemplation of the Third Intellect brings the Fourth Intellect and the sphere of Saturn into existence, the contemplation of the Fourth Intellect being brings the Fifth Intellect and the sphere of Jupiter into existence, and so on through the Tenth Intellect and the spheres of Mars, the Sun, Venus, Mercury, and the Moon. Thus Fārābī combines Ptolemy's planetary spheres with Neoplatonic emanationism and necessity into a philosophical cosmology that would become the fundamental tenet of all subsequent Islamic Hellenistic philosophers (falāsifa). In their view, the celestial heavens were the realm of celestial intellects, souls, spheres, and planets.

Fārābī's Commentary on Ptolemy's Almagest (Shar al‐Majisī) is his only strictly astronomical work. The text has not yet been edited, but a Russian translation has been published, based on Ibn Sīnā's shortened recension preserved in a British Library manuscript.

Selected References

Druart, Thérèse‐Anne (1978). “Astronomie et astrologie selon Farabi.” Bulletin de philosophie médiévale 20: 43–47.

——— (1979). “La second traité de Farabi sur la validité des affirmations basées sur la position des étoiles.”Bulletin de philosophie médiévale 21: 47–51.

Al‐ Fārābī, Abū Nasr (1948). Risāla fī fadīlat al‐ʿulūm wa‐ʾl‐sināʿāt. Hyderabad: Dāʾirat al‐Maʿārif.

——— (1949). Iāʾ al‐ʿulūm, edited by ʿUthmān Amīn. Cairo.

——— (1969). Shar al‐Majistī, translated into Russian by A. Kubesova and B. Rosenfeld. Alma Ata: Nakau.

——— (1982). “Nukat fīmā yaiu wa‐mā lā yaiu min akām al‐nujūm.” In Alfārābī's philosophische Abhandlungen aus Londoner, Leidener, und Berliner Handschriften, edited by Friedrich Dieterici, pp. 104–114. Osnabrück: Biblio Verlag.

——— (1985). Al‐Farabi On the Perfect State (Mabādiʾ ārāʾ ahl al‐madīna al‐fāila), edited and translated by Richard Walzer. Oxford: Clarendon Press.

——— (1986). Kitāb ārāʾ ahl al‐madīna al‐fāila, edited by Y. Karam, J. Chlala, and A. Jaussen. Beirut: Librairie Orientale.

Sezgin, Fuat (1978). Geschichte des arabischen Schrifttums. Vol. 6, Astronomie, pp. 195–196. Leiden: E. J. Brill.