Avicenna and The Canon of Medicine: Ibn Sina's Legacy

Avicenna, the Persian physician and philosopher Ibn Sina, completed The Canon of Medicine around 1025, while serving the princes of western Iran. The Canon brought together the medical knowledge of the ancient and Islamic worlds in one ordered system and became the standard medical textbook from Central Asia to Spain. Translated into Latin in the twelfth century, it was taught in European universities for some five hundred years, while his philosophical works shaped both Islamic and Christian thought.

Background: medicine and learning around the year 1000

By the late tenth century the Islamic world had absorbed a huge body of ancient science. Greek medical texts by Hippocrates and Galen, along with philosophy by Aristotle, had been translated into Arabic in Baghdad, notably by scholars linked to the House of Wisdom. Physicians such as Abu Bakr al-Razi (Rhazes) had already written major medical works based on these sources and on their own clinical experience.

Political power, however, was fragmented. In Central Asia the Samanid Empire ruled from Bukhara and was a great patron of Persian and Arabic learning, but it was collapsing by the 990s. Western Iran was divided between branches of the Buyid dynasty and smaller local rulers. Scholars moved from court to court, depending on the favour of princes who could be overthrown at any time.

Early life: a prodigy in Bukhara

Most of what is known about Ibn Sina’s early life comes from a short autobiography, completed after his death by his pupil and companion Abu Ubayd al-Juzjani. He was born around 980 at Afshana, a village near Bukhara, where his father was a local official in the Samanid administration.

According to this account, he had learned the Quran and much Arabic literature by the age of ten. He studied logic and mathematics, then natural science and medicine, which he found “not one of the difficult sciences”. By about sixteen he was treating patients. He said that he read Aristotle’s Metaphysics some forty times without understanding it, until a cheap copy of a commentary by al-Farabi bought in the market made its meaning clear.

At about seventeen he helped treat the Samanid amir Nuh II ibn Mansur during an illness. As a reward he was allowed to use the royal library, which he described as having rooms full of books arranged by subject. He later claimed that by the age of eighteen he had mastered all the sciences, and that afterwards he only deepened his knowledge.

A wandering scholar

When the Samanid state fell around 999 and his father died, Ibn Sina began a long life of travel. He worked at Gurganj in Khwarazm, then moved west, partly to avoid being summoned to the court of Mahmud of Ghazni. He spent time in Gorgan, near the Caspian Sea, where he began writing the Canon, and in Rayy.

In Hamadan he treated the Buyid ruler Shams al-Dawla and was appointed his vizier, the chief minister. The post was dangerous: the army mutinied against him, and he was at one point forced into hiding. After Shams al-Dawla’s death he was imprisoned for several months in a castle called Fardajan, where he continued to write.

Around 1024 he escaped to Isfahan and entered the service of its ruler, Ala al-Dawla, who gave him a stable life for his last years. He wrote prolifically, often dictating at night after a full day of official work. He fell ill during a military campaign and died in Hamadan in June 1037, aged about 57, where he was buried.

The Canon of Medicine

The Canon (al-Qanun fi al-Tibb, “the law of medicine”) was begun in Gorgan around 1012 and completed around 1025. Its aim was to present the whole of medicine as a single, logically organised science. It is divided into five books:

• Book I: general principles, including the theory of the four humours, anatomy, the causes and signs of disease, and the maintenance of health through diet, exercise and sleep.
• Book II: simple drugs, with around 800 medicinal substances from plants, animals and minerals, arranged in alphabetical order with their properties.
• Book III: diseases affecting particular parts of the body, ordered from head to toe.
• Book IV: conditions not limited to one organ, such as fevers, swellings, wounds, fractures and poisons.
• Book V: compound drugs, a formulary of medicines made from several ingredients.

The Canon’s medical theory was largely that of Galen, combined with Aristotle’s natural philosophy. Its strength lay in its clarity and completeness. Ibn Sina also added his own observations and refinements. He set out conditions for testing the effects of a drug, such as using a pure substance, testing it on a simple illness and observing whether its effects were consistent. He discussed the spread of some diseases through contact, water and soil, and described in detail the symptoms used in diagnosis, especially the pulse and urine.

The Book of Healing and Ibn Sina’s philosophy

Ibn Sina was as famous as a philosopher as he was as a physician. His Book of Healing (Kitab al-Shifa) is a vast encyclopedia of logic, natural science, mathematics and metaphysics. Its title means that it heals the soul from ignorance. He also wrote shorter works, such as The Book of Salvation (Kitab al-Najat), and the Danishnama-yi Ala’i in Persian, dedicated to Ala al-Dawla.

His best-known ideas include a proof of God as the “necessary existent”, a being whose existence depends on nothing else, and the distinction between a thing’s essence (what it is) and its existence (that it is). His “floating man” thought experiment imagined a person created in mid-air, cut off from all sensation, who would still know that he exists. Ibn Sina used it to argue that the soul is distinct from the body.

These ideas provoked strong reactions. The theologian al-Ghazali attacked several of Ibn Sina’s positions in The Incoherence of the Philosophers (1095), and the Andalusian philosopher Averroes later defended philosophy against al-Ghazali, while disagreeing with Ibn Sina on many points.

The Canon in Europe

In the twelfth century, after the Christian capture of Toledo, the city became a centre for translating Arabic works into Latin. There the Italian scholar Gerard of Cremona, who died in 1187, translated the Canon. Ibn Sina became known in Europe as Avicenna, and his philosophy also reached the Latin West, influencing thinkers such as Thomas Aquinas.

By the thirteenth century the Canon was a basic textbook in the medical faculties of the new universities. The first printed Latin edition appeared in Milan in 1473, and dozens of further editions followed. In 1593 the Medici Oriental Press in Rome printed the Arabic text. The historian Nancy Siraisi has shown how central the Canon remained to medical teaching in Italian universities such as Padua and Bologna in the sixteenth century, and it stayed on some curricula, for example at Montpellier and Louvain, into the seventeenth century.

Not everyone revered it. In 1527 the Swiss physician Paracelsus is said to have thrown a copy of the Canon into a bonfire in Basel to show his rejection of the old authorities. As anatomy, physiology and chemistry advanced, the Canon gradually lost its place. The anatomical work of Andreas Vesalius, published in 1543, and William Harvey’s account of the circulation of the blood in 1628 undermined key parts of the Galenic system on which it rested.

Myths and facts

“Avicenna was the father of modern medicine.” He was one of the most influential medical writers in history, but his medicine was based on the humoral theory of Galen, which modern medicine abandoned. His importance lies in organising and transmitting knowledge, not in founding modern medicine.

“He was an Arab.” Ibn Sina was Persian, born near Bukhara, though he wrote most of his works in Arabic, the scholarly language of the Islamic world. Iran, Uzbekistan, Tajikistan and the wider Islamic world all honour him today.

By the numbers

Timeline

• c. 980: Ibn Sina is born at Afshana, near Bukhara.
• c. 997: He treats the Samanid amir Nuh II and gains access to the royal library.
• c. 999: The Samanid state falls; Ibn Sina begins his travels.
• c. 1012: He begins The Canon of Medicine in Gorgan.
• c. 1015–1021: He serves as physician and vizier to Shams al-Dawla in Hamadan.
• c. 1024: He moves to Isfahan under Ala al-Dawla.
• c. 1025: The Canon of Medicine is completed.
• 1037, June: Ibn Sina dies in Hamadan.
• 12th century: Gerard of Cremona translates the Canon into Latin in Toledo.
• 1473: First printed Latin edition of the Canon appears in Milan.

Why it matters

The Canon of Medicine showed how a single scholar could turn centuries of scattered knowledge into a coherent system that others could learn and teach. Through it and through his philosophy, Ibn Sina linked ancient Greece, the Islamic world and medieval Europe, and his work remained part of medical education for half a millennium.