Six men whose work underpins the modern world, and whose names the West rarely connects to it.
The word algorithm is everywhere right now. It sorts feeds, screens job applications, sets prices and steers cars. Almost no one using it knows that it is a Persian surname, worn down over nine centuries until the man behind it disappeared into the term.
He is not the only one. A great deal of what Europe later called its own scientific inheritance was written first in Arabic, by scholars across Baghdad, Cairo, Cordoba and the wider Muslim world, between roughly the 9th and 13th centuries. Their books reached Europe through one place above all: Toledo, where in the 12th century Muslim, Christian and Jewish translators worked side by side to move the Arabic scientific library into Latin. Gerard of Cremona alone translated more than seventy works.
Something was lost in the transfer. An Arabic name does not fit cleanly into a Latin sentence, so the translators reshaped it. Ibn Sina became Avicenna. Ibn al-Haytham became Alhazen. The knowledge crossed over intact. The names, for the most part, did not.
Here are six of the men behind them.
1. Al-Khwarizmi – Algorithmi
In 9th century Baghdad, a Persian mathematician wrote a treatise with the word al-jabr in its title, meaning the restoration of something broken. Latin took the word and turned it into algebra. It then took his name. Al-Khwarizmi became Algorithmi in translation, and Algorithmi became algorithm. Nearly every automated system in use today carries a distorted version of his name. He was also responsible for bringing the Hindu decimal system westward, the reason the numerals in use across the world are not Roman ones.
2. Ibn Sina – Avicenna
He completed the Canon of Medicine around 1025, and European medical schools were still teaching from it six hundred years later. He is said to have memorised the Quran by the age of ten and to have been practising medicine by sixteen. Centuries before the microscope, he proposed that disease could spread through something unseen in water and air. Gerard of Cremona translated the Canon in Toledo, and the Latin name attached to it so firmly that the original was all but forgotten in the West.
3. Ibn al-Haytham – Alhazen
Held under house arrest in Cairo, by one account feigning madness to escape the anger of a caliph, he used the years of confinement to overturn an idea held since the Greeks: that the eye sends out rays in order to see. He demonstrated the opposite, that light enters the eye. He went further, arguing that no claim should be accepted until it has been tested by an experiment designed to disprove it, a principle that would become the scientific method six centuries before Europe formalised it. Kepler built directly on his Book of Optics, and the camera obscura descended from his work.
4. Al-Zahrawi – Abulcasis
Working in 10th century Cordoba, he produced a thirty-volume medical encyclopedia whose final section transformed surgery. He illustrated around two hundred instruments, many of his own design, a number of which remain recognisable in operating theatres today, among them forceps, scalpels, retractors and surgical hooks. He established that catgut dissolves within the body and used it for internal stitching, still standard practice. He is also credited with the plaster cast and the syringe. His work served as the principal surgical text in Europe for five centuries.
5. Ibn al-Nafis
In Damascus around 1242, at roughly twenty-nine, he challenged a thousand-year-old teaching of Galen, that blood passes through invisible pores in the wall of the heart. Those pores, he wrote, do not exist. Blood travels from the right side of the heart to the lungs, takes in air, and returns. This was the discovery of pulmonary circulation, three centuries before William Harvey described it in Europe. His manuscript lay unexamined in Berlin until 1924. He was never given a Latin name, because Europe did not know his work existed.
6. Al-Biruni
Around 1023, al-Biruni was at Nandana fort in the Salt Range, in present-day Jhelum district. Earlier scholars had estimated the size of the planet by measuring long distances between two cities and comparing the angle of the sun. He found a way to do it from a single point, climbing a hill of known height and measuring the slight dip of the horizon below the level line, then solving the resulting triangle. His figure for the Earth’s radius came to 6,339 kilometres, against the modern value of 6,371, an error of about one percent. The fort still stands.
None of this knowledge was ever truly hidden. The books were copied, translated, printed and taught across Europe for centuries. What went missing were the names, worn down syllable by syllable in the passage from Arabic into Latin. Algebra kept the word. Algorithm kept the man. Neither was recognised for what it was.
