Euclid: The Man Who May Not Have Existed — 8 Surprising Facts About the Father of Geometry

His book is the second most published in history. His algorithm is running on your phone right now. Every schoolchild knows his name. But, much like Pythagoras, we know almost nothing about him. Here is everything we managed to gather about Euclid.

What the Euclid Biography Is Missing: His Face

Not a single word describing Euclid’s appearance has survived. The bearded sage in Raphael’s fresco The School of Athens is pure artistic invention. Euclid is one of the most influential people in history — and we have absolutely no idea what he looked like.

A Biography Invented by Medieval Arab Scholars

Detailed but entirely fictitious biographical accounts appear in Islamic sources: born in Tyre (modern-day Lebanon), son of a man named Naucrates, grandson of Zenarchus, a Greek who lived in Damascus and worked as a carpenter. Modern historians regard all of this as fabrication, constructed to forge a connection between the great mathematician and the Arab world.

Confused with Another Man for Over 1,000 Years

For a full millennium, scholars conflated Euclid the mathematician with Euclid of Megara — a Socratic philosopher who lived roughly 100 years earlier. The error passed from manuscript to manuscript and even made it into the first printed edition of the Elements in 1482. The confusion was only resolved during the Renaissance.

The Lost Book on Mathematical Mistakes

One of the most intriguing of Euclid’s lost works is the Pseudaria — the “Book of Fallacies.” According to Proclus, it was written specifically for beginners: a catalogue of typical errors in geometric reasoning. In effect, Euclid invented learning-through-mistakes pedagogy about 2,300 years before it became fashionable.

Euclid Believed Eyes Fire Rays

In his treatise Optics — the oldest surviving Greek text on perspective — Euclid argued that vision works by the eye emitting rays that travel outward toward objects. The physics is completely wrong, but the mathematical model was so precise that it underpinned optics, perspective in painting, and navigation for more than 2,000 years.

The Euclid Algorithm That Still Runs Today

Euclid’s algorithm for finding the greatest common divisor, from Book 7 of the Elements, is the oldest non-trivial algorithm in history. Donald Knuth called it “the granddaddy of all algorithms.” The procedure is roughly 2,300 years old and is still in active use in modern cryptography, including RSA encryption.

The Second Most Published Book After the Bible

After the invention of the printing press, Euclid’s Elements (first edition: 1482) became the second most published book in history — over 1,000 editions. It remained the standard mathematics textbook from around 300 BC until the late 19th and early 20th centuries.

Did Euclid Even Exist? A Question the Euclid Biography Cannot Answer

There is not a single mention of Euclid by name from his own lifetime. The first confirmed reference appears in the work of Apollonius of Perga, decades later. Ancient mathematicians typically referred simply to “the author of the Elements.” Some medieval scholars suggested that “Euclid” was a corruption of Greek mathematical terminology rather than the name of a real person. It is possible that behind the name stood an entire group of scholars — much like Nicolas Bourbaki — but that is a story for another time.