From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 635-636
Kindī: Abū Yūsuf Yaʿqūb ibn Isḥāq al‐Kindī
Glen M. Cooper
Born probably Kūfa, (Iraq), circa 800
Died probably Baghdad, (Iraq), after 870
Kindī was a pivotal figure in the transmission of Greek science into the Islamic world. A polymath, he left approximately 260 treatises on various scientific and philosophical subjects, including optics, astronomy, arithmetic, geometry, medicine, music, and metaphysics. Only a few of these have survived. Little is known about his life.
Kindī arrived in Baghdad, the capital of the Islamic realm, during the reign of the ʿAbbāsid Caliph Maʾmūn (reigned: 813–833), when the Graeco–Arabic translation movement was in its early stages. Kindī enjoyed the favor of several caliphs, serving as tutor to the son of Caliph Muʿtaṣim (reigned: 833–842), under whom Kindī especially flourished, but he fell into disgrace under Caliph Mutawakkil (reigned: 847–861). His library was confiscated, and he was publicly beaten, possibly due to court intrigue. According to some accounts, Kindī's library was eventually restored.
Although he is remembered primarily as “the philosopher of the Arabs,” Kindī was active in many areas of scientific research. His work is significant in the history of astronomy for a number of reasons. First, he founded the philosophical program of study, centering on the works of Aristotle, without which the pursuit of Greek‐inspired astronomy, and the many contributions made by Islamic theoretical astronomers, would have been impossible. He taught that philosophical knowledge can be acquired only through years of sustained study. The sciences of the quadrivium (arithmetic, geometry, music, and astronomy) must be mastered before the student can understand Aristotle's writings on logic, physics, ethics, and metaphysics, or other sciences such as astrology and medicine. Kindī's approach toward the ancient sciences was to complete them, and his strategy of presentation was to combine observation with the Euclidean “axiomatic method” of rational demonstration, a perspective he presented in a treatise entitled That Philosophy Can Be Acquired Only by Mathematical Discipline. Kindī did not slavishly follow Aristotle or other Greek philosophers. For example, he produced an ingenious argument against the infinite magnitude of the Universe; by employing a skillful reductio ad absurdum argument, Kindī showed how the notion of actual infinity leads to paradoxes.
Second, Kindī began the systematic formulation of a scientific Arabic terminology based on Greek concepts. This idiom formed the groundwork for the later philosophical and scientific contributions of Fārābī, Ibn Sīnā, Ghazālī, Ibn Rushd, and others. And through Latin translations of the 12th century, Kindī's influence also extended into Europe.
Third, Kindī also created an Islamic idiom, showing how Greek ideas could be adapted into the Islamic metaphysical framework, without detriment to either. Despite these efforts, however, Kindī clashed with contemporary Islamic theologians, who often viewed the Greek sciences with suspicion.
In terms of actual work in astronomy and cosmology, Sezgin lists some 30 works, only 13 or so being extant. Of those that are extant, five are general or cosmological works (one being a paraphrase of the Almagest), three concern instruments, and the rest are on particular topics. None of these seem particularly original but indicate an interest in making the Greek scientific heritage better known to a wider audience. Kindī also wrote extensively on astrological topics and was responsible for introducing Abū Maʿshar to astrology; he was to become the most influential astrological authority in both the Arabic and the Latin Middle Ages. Finally, it is worth mentioning that Kindī was also interested in optics, a subject important to astronomy, and developed a new analytical approach, punctiform analysis, whereby each point of the visible object is perceived by an individual ray coming from the eye.
D'Alverny, M. T. and F. Hurdy. “Al‐Kindi, De Radiis.” Archives d'histoire doctrinale et littéraire du moyen‐âge 41:139–260.
Endress, Gerhard (1997). “The Circle of Al‐Kindī.” In The Ancient Tradition in Christian and Islamic Hellenism: Studies on the Transmission of Greek Philosophy and Sciences, edited by Gerhard Endress and Remke Kruk, pp. 43–76. Leiden: Research School CNWS. (Contains a detailed discussion of the figures associated with Kindī's circle, the philosophers, scientists, and translations, and describes the scope of their work.)
Gutas, Dimitri (1998). Greek Thought, Arabic Culture: The Graeco–Arabic Translation Movement in Baghdad and Early ʿAbbāsid Society (2nd–4th/8th–10th centuries). London: Routledge.
Ivry, Alfred L. (1974). Al‐Kindī's Metaphysics. Albany: State University of New York Press. (A work fundamental to understanding Kindī's philosophy.)
Lindberg, David C. (1976). “Al‐Kindi's Critique of Euclid's Theory of Vision.” Chap. 2 in Theories of Vision from al‐Kindi to Kepler,. pp. 18–32. Chicago: University of Chicago Press.
Rescher, Nicholas (1964). Al‐Kindī: An Annotated Bibliography. Pittsburgh: University of Pittsburgh Press. (Somewhat dated, but still very useful.)
Rescher, Nicholas and Haig Khatchadourian (1965). “Al‐Kindī's Epistle on the Finitude of the Universe.” Isis 56: 426–433.
Rosenthal, F. (1956). “Al‐Kindī and Ptolemy.” In Studi orientalistici in onore di Giorgio Levi Della Vida. Vol. 2, pp. 436–456. Rome: Instituto per l'Oriente. (Contains a discussion of Kindī's paraphrase of the Almagest, placing it within the context of Kindī's other writings and of the understanding of Ptolemaic astronomy of Kindī's time.)
Sezgin, Fuat. Geschichte des arabischen Schrifttums. Vol. 5, Mathematik (1974): 255–259; Vol. 6, Astronomie (1978): 151–155; Vol. 7, Astrologie–Meteorologie und Verwandtes (1979): 130–134. Leiden: E. J. Brill.
Walzer, R. (1957). “New Studies on al‐Kindi.” Oriens 10: 203–232. (Excellent summary of the then available treatises by Kindī.)