Avicenna

• 1. Introduction

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  By the age of ten, Avicenna had memorized the entire Quran. He was born around 980 in the village of Afshana in Transoxiana, into a Persian family, and his curiosity would carry him through the libraries of Balkh, Khwarazm, Gorgan, Rey, Isfahan and Hamadan. Known in Arabic as Ibn Sina, and in the West by the Latinized name Avicenna, he became a preeminent philosopher and physician of the Muslim world. He died on the 22nd of June 1037.

  He is often described as the father of early modern medicine. He is believed to have written around 450 works, of which roughly 240 have survived. Yet a list of titles tells you little about the man who debated the sharpest scholars of his age and once cured a prince who believed he was a cow. How did a boy in Bukhara become ranked beside Hippocrates and Galen? What did he mean when he asked his readers to imagine a man falling through empty air? And why was a charge laid against him in Hamadan so grave that, in one historian's words, its seriousness cannot be underestimated? Those questions begin in a single, restless lifetime spent moving from court to court.

• 2. Courts And Patrons

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  At seventeen, Avicenna was made a physician of the Samanid ruler Nuh II, and by twenty-one his father had died. He inherited an administrative post, possibly succeeding his father as governor of Harmaytan. The fall of the Samanid Empire, after the Kara-Khanid Khanate captured Bukhara and imprisoned the emir Abd al-Malik II, left him exposed because of his close ties to that ruling house.

  Gurganj, the capital of Khwarazm, drew him next, where he entered the service of the Ma'munid ruler Abu al-Hasan Ali through the minister Abu'l-Husayn as-Sahi, a patron of Greek sciences. Under the Ma'munids, Gurganj became a centre of learning, gathering figures such as the mathematician Abu Nasr Mansur and the physician ibn al-Khammar.

  Necessity drove him west in 1012, through the Khurasani cities of Nasa, Abivard, Tus, Samangan and Jajarm. He hoped to reach the Ziyarid ruler Qabus of Gorgan, a cultivated patron of writing, only to learn that Qabus had been dead since the winter of 1013. In Gorgan he met Abu 'Ubayd al-Juzjani, who became his pupil and lifelong companion.

  Around 1014 he reached Ray and served the Buyid amir Majd al-Dawla and his mother Sayyida Shirin, the realm's de facto ruler. He treated Majd al-Dawla for melancholia, and during this period finished The Canon of Medicine. His most settled years came later, in Isfahan, under the Kakuyid ruler Ala al-Dawla. Juzjani records that the ruler gave Avicenna the respect and esteem which someone like him deserved.

• 3. Prison And Vizier

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  Shams al-Dawla, a rising Buyid amir, summoned Avicenna to treat him, then forced him to become his vizier. Avicenna sometimes clashed with the amir's troops, yet remained in the office until Shams al-Dawla died of colic in 1021. Rather than serve the successor Sama' al-Dawla, he went into hiding with his patron Abu Ghalib al-Attar to wait for a better moment.

  It was in Attar's home that Avicenna completed The Book of Healing, writing fifty pages a day. The Buyid court in Hamadan, and particularly the Kurdish vizier Taj al-Mulk, suspected him of secret correspondence with Ala al-Dawla, the Kakuyid ruler of Isfahan. They ransacked Attar's house and imprisoned Avicenna in the fortress of Fardajan, outside Hamadan. Juzjani blames one of his informers for the capture.

  Four months passed before Ala al-Dawla captured Hamadan and ended Sama al-Dawla's reign. The arrest had a strange consequence for thought itself. Inside Fardajan, Avicenna composed the thought experiment that would carry his name into later philosophy.

• 4. The Floating Man

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  Imagine a person created in a single stroke, perfect and complete, but with his vision obscured so he perceives nothing outside himself. Avicenna asked his readers to picture this figure falling through air or a void, his limbs separated so they never touch. This is the Floating Man, sometimes called the falling man, written to demonstrate human self-awareness and the immateriality of the soul.

  The question Avicenna posed is simple. Can such a person be assured of his own existence? He argued that the man would not doubt that his self exists, even while asserting nothing about a hand, a heart, or a brain. The first knowledge of the flying person would be the bare statement, I am, affirming his essence.

  Because that essence cannot be the body, since the man has no sensation, Avicenna concluded that the soul is a substance, independent of the body and immaterial. He developed this argument in the psychology of The Book of Healing. The historian's note is that this reasoning has an affinity with Descartes's later cogito argument, an echo arriving centuries before Descartes wrote.

• 5. The Canon Of Medicine

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  Five volumes make up The Canon of Medicine, Avicenna's comprehensive medical work. The first book covers general principles, the second outlines medicinal substances and their properties, the third treats disease and remedies, the fourth concerns the maintenance of health, and the fifth addresses specific ailments and their cures. It served as a standard textbook in the Islamic world and Europe, remaining in use as late as 1650.

  Inside its pages Avicenna postulated that invisible tainted organisms were associated with disease, and recommended isolating the ill to reduce transmission. He recognized the contagious nature of tuberculosis and the spread of disease through water and soil. He described 760 different drugs in one book, the most authentic work on the subject for that era.

  The heart drew some of his most original work. Avicenna corrected earlier pulse information from Galen and Chinese physicians, earning the title pioneer of pulsology. In the third book of The Canon, he described the symptom of carotid sinus hypersensitivity, and he linked inner feelings to the pulse rate in what he called the love-sickness phenomenon. Among medieval European scholars he came to be ranked beside Hippocrates and Galen as princeps medicorum, the prince of physicians.

• 6. Essence And Existence

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  Following the lead of al-Farabi, Avicenna opened a full inquiry into the question of being, distinguishing between essence and existence. He argued that the fact of existence cannot be inferred from the essence of a thing. Existence must come from an agent-cause that gives being to an essence, what he called the efficient cause, which gives being to another and is simultaneous with its effect.

  His analysis turned on three modes of being: impossibility, contingency and necessity. The impossible cannot exist. The contingent in itself has the potential to be or not to be without contradiction, and becomes actual only through an external cause. The necessary being due to itself is true in itself, the source of its own being, and is what always exists.

  The Necessary, Avicenna held, has no quiddity other than existence, and is One. It has no genus, no definition, no counterpart and no opposite, and stands detached from matter, quality, quantity, place, situation and time. From this he built the argument later known as the Proof of the Truthful, an entity that cannot not exist, which he identified with God. The present-day historian Peter Adamson called it one of the most influential medieval arguments for God's existence.

• 7. Nature And Experiment

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  In the Al-Burhan section of The Book of Healing, Avicenna asked how a scientist acquires the first principles of a science without inferring them from more basic premises. He criticized Aristotelian induction, arguing that it does not deliver the absolute and certain premises it claims, and in its place he developed a method of examination and experimentation, called tajriba.

  The earth offered him another laboratory. Writing on the formation of mountains, he proposed they could be the effect of upheavals of the crust during a violent earthquake, or the work of water cutting new routes and denuding valleys, and noted that such changes would require a long period of time. In mechanics he distinguished inclination from force, arguing that a thrown object carries an inclination, or mayl, and that projectile motion in a vacuum would not cease.

  The stars drew his skepticism. Avicenna wrote an attack on astrology, citing passages from the Quran to dispute its power to foretell the future, while treating mathematical astronomy as a separate discipline. He claimed to have observed the transit of Venus, possibly the transit of the 24th of May 1032, though scholars question whether he could have seen it and suggest he may have mistaken a sunspot. On alchemy he broke with his peers, disputing the transmutation of substances and insisting that practitioners could produce only the appearance of change.

• 8. An Enduring Name

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  Dante placed Avicenna in Limbo among the virtuous non-Christian thinkers of his Divine Comedy, alongside Virgil, Averroes, Homer, Socrates, Plato and Saladin. The Book of Healing reached Europe in a partial Latin translation, under the title Sufficientia, some fifty years after its composition. His psychology influenced William of Auvergne and Albertus Magnus, while his metaphysics shaped the thought of Thomas Aquinas, and Johannes Kepler cited his opinion on planetary motions.

  George Sarton, author of The History of Science, called Avicenna one of the greatest thinkers and medical scholars in history, and the most famous scientist of Islam. His theology and philosophy formed part of the core curriculum at Islamic religious schools until the 19th century. A scholar of his work, Robert Wisnovsky, described him as the central figure in the long history of the rational sciences in Islam.

  His name still travels. There is a crater on the Moon named Avicenna, and a peak on the Kyrgyzstan-Tajikistan border called Ibn Sina Peak. The Avicenna Prize, established in 2003, is awarded every two years by UNESCO for achievements in the ethics of science. He even appears in the 2025 video game Civilization VII as a Great Person for the Abbasid civilization, where he creates a hospital. The traveler who once moved from court to court out of necessity now lends his name to hospitals, universities and a mausoleum in Hamadan, the city where he was buried.