AL-KINDĪ, ABŪ YŪSUF YA'QŪB IBN-ISḤĀQ

First outstanding scholar of Arab descent, hence his honorific title Faylasüf al-‘Arab (the philosopher of the Arabs). His surname indicates descent from the noble South Arabian tribe of Kindah.

Life. Al-Kindī was born about 801 in al-Kūfah (Kufa), Iraq, where his father was a governor under the ‘Abbāsids. He studied at Baghdad, where he flourished and died about 873. As a young man he held positions in the courts of al-Ma’mūm (813–833) and al-Mu’taṣim (833–842), whose son he tutored. He dedicated some of his works to his pupil. Baghdad was then not only the political but also the intellectual capital of Islam. It was especially noted as a center of translation from Hindu through Persian, and from Greek through Syriac into Arabic. Al-Kindī himself is credited with translating, among other Greek works, those of Ptolemy; but recent research seems to indicate that he, whose philosophical vocabulary shows many Syriacisms, depended upon translations made by Christian Syrians, whose Arabic he may have revised. The philosophy he developed was eclectic, concerned primarily with reconciling and combining—in Neoplatonic fashion—the views of Plato and Aristotle. He followed the Neo-Pythagoreans in attaching mystic values to numerals, making mathematics the basis of science, especially of physics, and in not excluding medicine. In his moral philosophy he shared with his contemporaries, the Mu’tazilites, the views of Socrates on virtuous living and the deprecation of luxury.

Al-Kindī is ranked among the 12 greatest minds of Islam, but he was more encyclopedic than creative. His industry and literary activity contributed to the early diffusion of Greek learning and Persian-Indian science. Hardly a known scientific field—mathematics, physics, optics, medicine, astrology, geography, music, logic, poetry, or theology—was alien to his pen.

Works. For the celebration of al-Kindī's 1,000th anniversary in Baghdad (1962), Richard J. McCarthy, SJ, published a list of 361 titles attributed to him [Al-Taṣānīf al-Mansūbah ilā Faylasūf al-‘Arab (Baghdad 1962)]. The list begins with a work on philosophy and ends with one on swords. A short treatise by him on the manufacture of swords was published on the same occasion ['Aml al-Suyūf (Baghdad 1962)]. One treatise in the list deals with the art of cooking. In the titles, the names of Socrates, Aristotle, Plato, Euclid, Archimedes, Ptolemy, Hippocrates, and Galen appear, some more than once. Most of the works are treatises, some still in manuscript form, others now lost; a few may be spurious. Those extant in Latin are perhaps more numerous than those in Arabic. Alkindus, as he was designated in Latin, was well known to scholars throughout medieval times, but in the Arab world his influence waned after the 10th century. He was eclipsed by other Arab-Muslim philosophers both in Spain and in the East. Perhaps some of his books were lost when the conservative Caliph al-Mutawakkil (847–861) restored orthodoxy, disgraced and humiliated him, and seized his library. It was to the school of translators that flourished in Toledo under the patronage of Archbishop Raymond that the Latin world owed its knowledge of this Arab philosopher. gerard of cremona (d. 1187) was especially interested in al-Kindī, as was John of Seville (Joannes Hispalensis), a Christian convert from Judaism. At least some of the medical translations by Gerard of Cremona were included in the De medicinarum compositarum gradibus investigandis, published at Strassburg in 1531. In it al-Kindī propounds the extraordinary theory that mathematics is the basis of composite medicine and that doxology is a mathematical art. Alchemy, then considered an important science, was deprecated by al-Kindī. He did not believe it possible to transform base metal into gold or silver (the chief preoccupation of alchemists in his day). In Arabic the first large collection of al-Kindī [Rasā’il al-Kindī al-Falsafīyah, ed. Muḥammad ‘Abd-al-Wahhāb abū-Rīdah (Cairo)], containing 25 philosophical treatises, was not published until 1950–53.

One of al-Kindī's principal works dealt with geometrical and physiological aspects. Based on the optics of Euclid in Theon's recension, it was rendered into Latin as De aspectibus and was widely used in both Latin and Arabic until superseded by the greater work of Alhazen (Ibn al-Haytham). In his treatise, al-Kindī discusses the passage of light in a straight line and the process of vision directly, or through a looking glass. He recognizes that while in smell, taste, hearing, and touch the sense receives impressions from outside objects, in the case of vision the sense grasps its object instantaneously and in an active manner. In a treatise, extant in Latin, on the blue color of the sky he recognizes the effect of atoms of dust and vapor.

The earliest Arabic works on music that have come down to us are the five compiled by al-Kindī. They contain a determination of pitch and a description of rhythm (īqā ’) as a constituent of Arab music, indicating a knowledge of measured song, or mensural music, in Islam centuries earlier than in Christendom. In music, which he renders as mūsīqī in Arabic, he was clearly indebted to the Greeks, as he was in other fields, such as astronomy. Although celebrated as an astrologer, he dealt with exact astronomical measurements.

Primarily a natural philosopher, al-Kindī devoted works to the soul (nafs ), the intelligence (' aql ), and to the relationship of the two. To him the world as a whole was the work of an external force, the divine intelligence. Between God and the world of matter lay the world of the soul. The human soul is an emanation of this world soul. Purely Islamic issues did not escape his attention. In one treatise he takes up the question of tawḥīd, the dogma of the unity of God, and in other works he attempts to refute both dualists and disbelievers.

Bibliography: t. j. de boer, The History of Philosophy in Islam, tr. e. r. jones (London 1903). c. brockelmann, Geschichte der arabischen Literatur, 2 v. (2d ed. Leiden 1943–49) 1:230–231. g. sarton, Introduction to the History of Science, 3 v. in 5 (Baltimore 1927–48) 1:559–560. a. nagy, Die philosophischen Abhandlungen des Ja‘qüb ben Ishäq al-Kindï Beiträge zur Geschichte der Philosophie und Theologie des Mittelalters 2.5 (1897).

[p. k. hitti]