Avicenna

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Avicenna — the Latinized name of Abū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā, known in the Islamic world simply as Ibn Sīnā — was a Persian philosopher and physician active across the eastern lands of the Abbasid world in the late tenth and early eleventh centuries. He is conventionally dated c.980 to 1037. More than any single figure he gave medieval Islamic philosophy its systematic shape, and through Latin translation he became one of the authorities the Christian schoolmen had to answer.

The biography is partly his own. A short autobiography, continued by a pupil, records a precocious youth in the region of Bukhara who claimed to have mastered the available sciences while still young and to have read Aristotle’s Metaphysics many times over before a commentary unlocked it. The rest was a working life spent in the service of various princes, writing, by tradition, in the intervals of court duty and on the move. Two works carried his name farthest. The Canon of Medicine organized Greek and Arabic medicine into a single encyclopedia that was still taught in European universities centuries later. The Book of Healing — despite the title, a vast philosophical summa covering logic, natural science, mathematics, and metaphysics — was the vehicle of his thought.

At its center lies a distinction that scholarship credits him with making decisive: between what a thing is and that it is — essence and existence. Everything in the world, he argued, is in itself merely possible; its existence is something added, received from outside. Follow the chain of what depends on another and it must end in a being whose existence is not received but belongs to it by its own nature — the Necessary Existent, from which all else proceeds. From this single source the orders of being emanate in a graded series, the Aristotelian heavens turning through a hierarchy of intellects, an architecture visibly indebted to the Neoplatonism that had reached Arabic readers partly under Aristotle’s name. The human rational soul, on his account, is immaterial and survives the body, perfected by knowledge.

His influence ran in more than one direction. Within Islamic thought he became the philosopher to refute or absorb: al-Ghazālī attacked central theses of the falsafa he represented, while later traditions, including the Illuminationist current, built on and transformed his work. In the Latin West, translated at Toledo, “Avicenna” supplied the schoolmen with arguments on the soul, on God’s necessity, and on the relation of essence to existence that Aquinas and others took up, adapted, and contested. Later esoteric writers have at times claimed him for an inner tradition, drawn to his accounts of prophecy, intuition, and a few visionary allegories; the connection is real in those late texts but slight beside the systematic philosopher the manuscripts mainly preserve. What the record holds steadiest is the architecture itself — a world hung from a single necessary being, reasoned through to the end.

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