Isaac Israeli

Works

• c. 920Book of Definitions

  Collection of definitions of philosophical terms – philosophy, wisdom, intellect, soul, nature, reason, love – largely drawn from al-Kindi’s treatise on definitions; it survives mainly in Latin and Hebrew translation and was quoted by scholastic authors, among them Thomas Aquinas.

• c. 920Book of Elements

  Treatise on the four elements in the tradition of Aristotle and Galen, preserved in Hebrew and Latin; Maimonides judged it, with the Book of Definitions, worthless as philosophy, since its author had been only a physician.

Position

Isaac Israeli is on the map as the first Jewish Neoplatonist of the Middle Ages and as an early witness to the spread of al-Kindi’s philosophy across the Mediterranean. His Book of Definitions collects definitions of philosophy, wisdom, intellect, soul, nature and other terms, many of them taken from al-Kindi’s treatise on definitions; philosophy is defined, among other ways, as becoming like the works of the Creator as far as humanly possible, and as knowledge of oneself. In the Book of Substances and the Book on Spirit and Soul he describes the world as created by God’s will and power: first come first matter and first form, which together make up wisdom or intellect; from them follow, by emanation, the rational, animal and vegetative souls and the sphere, each lower stage arising as a “shadow” of the higher – a point at which he departs from al-Kindi. The human soul can rise through purification and knowledge to the light of wisdom and unite with it, which he describes as its true reward. In the Book of Elements he discussed the four elements in dialogue with Aristotle and Galen. Jewish authors in Spain and Provence read his works, and in Latin they were quoted by Gundissalinus, Albertus Magnus, Thomas Aquinas, Bonaventure and others; Thomas’s attribution to him of the definition of truth as the adequation of thing and intellect is, however, a mistake. Maimonides, writing to his translator Samuel ibn Tibbon in 1199, dismissed the Book of Definitions and the Book of Elements as idle fancies, since Isaac had been “only a physician”. Modern study of his thought rests largely on the edition and commentary of Alexander Altmann and Samuel Stern (1958).

Life & context

Isaac ben Solomon Israeli was born in Egypt around 855; little is known of his early life. He became known as a physician and moved to Kairouan in Ifriqiya, in present-day Tunisia, where he served the last Aghlabid emir and then, from 909, the first Fatimid caliph, ʿUbayd Allah al-Mahdi. Later reports say that he never married and lived to a great age; the date of his death is uncertain, and modern scholars place it around 955, while Wikidata gives 932. He wrote in Arabic on medicine – on fevers, foods and urine – and on philosophy. Constantine the African translated his medical works into Latin in the eleventh century, and they were taught at Salerno and at European universities; his philosophical treatises reached Latin and Hebrew readers in the twelfth and thirteenth centuries. The physician Dunash ibn Tamim is named as his student in Kairouan.

Further main works

• Book of Substances (Kitāb al-jawāhir, fragments)
• Book on Spirit and Soul
• Medical works on fevers, foods and urine (Latin translations by Constantine the African)