Recognized as one of the earliest Jewish Neoplatonist writers, Isaac ben Solomon Israeli (ca. 855-955) influenced Muslim, Jewish, and Christian scholars through the Middle Ages. A native of Egypt who wrote in Arabic, Israeli explored definitions of such terms as imagination, sense-perception, desire, love, creation, and 'coming-to-be' in his writings. This classic volume contains English translations of Israeli's philosophical writings, including the "Book of Definitions", the "Book of Substances", and the "Book on Spirit and Soul". Additionally, Isaac Israeli features a biographical sketch of the philosopher and extensive notes and comments on the texts, as well as a survey and appraisal of his philosophy. Restored to print for the first time in decades, Isaac Israeli will be essential reading for students and scholars of medieval philosophy and Jewish studies.