Avicenna (a.k.a. Avicenna of Balkh; Ibn Sina; Shaykh Al-Ra’ees Abu Ali Al-Hussein Ibn Abdullah Ibn Sina Balkhi) was one of the most influential philosophers and scientists at the turn of the first millenium, and can rightly be named as the first of the Islamic philosophers.
He was born and raised in Balkh ~980 AD (Persia; Shi’ite; modern-day Uzbekistan). He was a very avid learner, having learned the Qur’an by age 10 and learning Arabic (really, Indian) arithmetic at a greengrocer’s. On noticing his prowess, his father moved him to nearby Bukhara, at the time the largest cultural center and capital of the Samanid empire (Sunni), giving him the opportunity to study under the greatest scholars of the time. Among other things, he studied Islamic law under Ismail al-Zahid. He read Aristotle’s Physics and Metaphysics and Ptolemy’s Almagest (medieval cosmology and astronomy), before turning to Galen‘s 129 books. Then he turned 18. Having used his medical knowledge to cure the prince, he had thus gained the court’s favour and was allowed unlimited access to one of the world’s largest libraries. He used it well, and by age 21, he was widely-acknowledged as the best physician in the world, as well as the msot well-learned person – as he says in his autobiography, he had learned everything there had been to learn (the only subject he had trouble grasping was metaphysics).
Political changes of the time, including the conquest of Bukhara by the Ghaznavids, forced him to wander to other areas of Greater Khorasan before eventually settling in Hamadan, where he not only worked as a physician, but was also a vizier. This lasted until 1022 AD, when Hamadan’s ruler died and Avicenna was sentenced to prison. Upon release, he was invited by Ala ad-Dawlah of Ishafan, and spent the last 14 years of his life in his court, dying in 1037 at the age of 57.
The former is a masterful compendium of philosophy, going through Avicenna’s thoughts about logic, psychology, maths, astronomy, music and metaphysis, and allows us to place him squarely as an Aristotelean and Neoplatonist – further emphasising just how learned he was to be aware of such sources.
The Canon is, simply put, an encyclopaedia of all the knowledge known at the time about medicine, drawing not only from his own experience and research, but also from his Greek and Roman forebears. It was complete enough to have remained the main resource for over 6 centuries.
His research was extremely widespread, typical of the luminaries and polymaths of the time who didn’t have to spend years specialising in a subject to be able to contribute new knowledge (as is the case today). His work was especially prevalent in physics, where he researched gravity, energy (heat and light), forces, and the connection between time and motion (the idea of the fluxus formae is Avicenna’s). Notably, he was also opposed to alchemy, viewing metals as being immutable and having fundamental differences that made them different metals.
He also did some theological work. For example, his Book of Directives and Remarks describes how one should go about finding God (who Avicenna viewed as the whole of existence, so I guess we would classify him as a deist).
An excellent overview of Avicennian thought can be found in Wisnovsky (2005).
His influence was tremendous and there is no way I can review it, as just about every scholar between Avicenna and the Renaissance had to be intimately familiar with his work.
Avicenna, in my non-scholarly opinion, counts as one of the earliest scientists and freethinkers. Sure, he was firmly grounded in Islamic teachings, but it is clear from his work that he put the natural world first and theology second. For example, he went against Islamic teaching and advocated determinism, as had Aristotle before him. This earned Avicenna the ire of Averroes, who said that determinism was heretical and sought to reconcile Avicennian and Aristotelean logic with indeterminism – a daunting task (and this is not the only place where Avicenna and Averroes disagreed).
Averroes wasn’t the only person to brand him a heretic. Having adopted and expanded on Aristotle, he was denounced as a kafir by al-Ghazzali. All of these would not have affected Avicenna though. He was a true philosopher, by Socratic definition: a lover of wisdom.
[Written up at the request of a reader.]
Wisnowsky R. 2005. Avicenna and the Avicennian Tradition. In: Adamson P & Taylor RC. The Cambridge Companion to Arabic Philosophy.