Al-Farabi (d. 950 AD), was perhaps the most original and influential of all Muslim philosophers of the Middle Ages. His intellectual activity spanned over areas as different as music, medicine, political theory, linguistics, logic, metaphysics, religion and philosophy at large. Great thinkers within the Islamic world from Ibn Bajjah to Ibn Rushd, as well as many outside it, such as Maimonides, St Thomas Aquinas and Spinoza refer to his works with great deference. Al-Farabis main contribution is the co-systematization of various spiritual disciplines in Islamic non-traditional culture, using them in a sophisticated manner for promoting a universalistic world-view. This edition consists of two volumes; volume one quotes the Arabic text of al-Farabi's philosophical definitions and those of parallel authors, and volume two contains an English translation, an interpretative essay on al-Farabi and detailed indices.