The greatest library of the ancient world was founded by the Ptolemaic dynasty at Alexandria in the 3rd century B.C.E. It is said that the library possessed hundreds of thousands of scrolls. No ship was allowed to enter the harbor at Alexandria without surrendering any book it carried for copying by the library scribes. As befits a city with so superb an institution of learning, Alexandria became for several centuries a center for creative science and mathematics. Euclid, Eudoxus, Hipparchus, Eratosthenses, Aristarchus, and Archimedes are just a few of the famous names associated with Alexandria. Their achievements were considerable, not least of which was measuring the size of the Earth and the sizes and distances of the Sun and Moon. When Alexandrian science collapsed, it would be a millennium-and-a-half before humans again achieved the same level of scientific learning.
Science thrives on free access to knowledge, which is exactly what the Alexandrian library provided. Science also thrives on social stability and secular values. Unfortunately, the library fell victim to political intrigue and religious intolerance. The first crisis came when Julius Caesar appeared on the scene in the middle of the 1st century B.C.E., at a time when Egypt was co-ruled by Cleopatra and her brother Ptolemy. Caesar intruded himself into local squabbles and was soon besieged in the city by allies of Ptolemy. It appears that a substantial number of books went up in smoke during the ensuing troubles.
The final destruction of the Alexandrian library was left to the Arab emir Amru, who captured the city in 642 C.E.. According to one tradition, Amru wrote to his Caliph Omar asking what to do with the tens of thousands of papyrus scrolls that were part of the fallen city's treasure. The Caliph's answered: "If the contents of the books accord with the Book of Allah, we do not need them, because in that case the Book of Allah is more than enough. If, on the other hand, they contain anything contrary to the Book of Allah, you must proceed with their destruction." Amru distributed the books to the city's thousands of bath houses to use as fuel for heating the water. It took six months to burn them all. Is the story true? Who knows. Scholars debate the authenticity of the sources. But even if the tale is apocryphal, it embodies a truth: religious dogma and public libraries are not congenial companions.