What was the Library of Alexandria?

The Library of Alexandria, founded in the early 3rd century BCE under the Ptolemaic dynasty, was the most ambitious intellectual project of the ancient world. Part of a larger research institution called the Mouseion (Museum — literally 'temple of the Muses'), it aimed to collect all the world's knowledge in a single location. At its height, it may have housed between 400,000 and 700,000 scrolls, though ancient estimates vary widely.

The Ptolemaic kings pursued acquisition with extraordinary zeal. Ships entering Alexandria's harbor were searched for books, which were copied (or sometimes confiscated). Ptolemy III reportedly borrowed the original manuscripts of the great Athenian tragedians from Athens, forfeited the deposit he'd paid to guarantee their return, and kept the originals. Scholars from across the Mediterranean were invited — and funded — to study, research, and write at the Library.

The results were remarkable. Euclid wrote his Elements — the foundational text of geometry — in Alexandria. Eratosthenes calculated the Earth's circumference to within a few percent of the correct value. Aristarchus proposed a heliocentric model of the solar system, anticipating Copernicus by 1,800 years. The Septuagint — the Greek translation of the Hebrew Bible — was produced there. Callimachus created the Pinakes, essentially the first library catalog.

The Library's destruction is often attributed to a single catastrophic event — Caesar's fire in 48 BCE is the most popular candidate — but the reality was more gradual. The Library suffered multiple incidents of damage over several centuries, and the decline of Ptolemaic royal patronage, followed by Roman indifference and eventually religious conflict, contributed to its slow disappearance. What was lost — the bulk of ancient Greek literature, scientific works, and historical records — is incalculable.