Three theories exist regarding destruction of the greatest repository of knowledge up to that time, the Great Alexandrian Library.
Theory 1 is that a Christian mob attacked and burned the library and its contents, along with its female Chief Librarian on the grounds that its contents included information about witchcraft.
Theory 2 is that the same earthquake which brought down the Alexandrian Lighthouse also destroyed the Library.
Below is another take on the same subject, which the reader might find interesting.
lius Ceasar set fire to his own ships in the harbor of Alexandria during a siege against Ptolemy XIV- Cleopatra’s brother. He was trying to clear the wharf and block Ptolemy’s own ships, when the fire spread to the docks and surrounding buildings. Scholars believe that the part of the library that caught fire was a warehouse containing excess texts, not the library itself. If it was damaged at all, it was quickly repaired or rebuilt. Strabo writes about visiting it, and Plutarch wrote about a gift given to Cleopatra (by Mark Antony) of 200,000 scrolls from the library. And whether or not Plutarch’s account was accurate or propaganda against Mark, it couldn’t have been claimed either way if the library had already been destroyed.
The Serapeum of Alexandria: a wing of the great library.
So, then- what was it that completely destroyed the library?
Budget cuts, mostly. Yeah, you heard me right.
In the beginning, the library had been stocked with nearly every text the Ptolemaic Dynasty could get their hands on. (And they were really wealthy at the time). They also kept a lot of scholars there, people who could live without paying room, board, or taxes, and were given a salary as long as they gave lectures, taught a few classes, and copied a text or two. Archimedes is said to have invented his famous screw there.
And Eratosthenes came weirdly close to determining the exact circumference of the earth. He also determined that there were 365 days in a year. (366 every 4th year)
A picture depicting Eratosthenes’ method.
After Ptolemy VII was murdered, Ptolemy VIII set out to punish everyone who supported the guy. Which meant a lot of the library’s inhabitants. Most were driven out.
The library was already partly neglected by the time Julius Caesar came around. His fire didn’t help, certainly. Those scholars who had been ejected from Alexandria went elsewhere and built new libraries, and while the Library of Alexandria dwindled, other places flourished. Alexandria had other, smaller libraries built around the city, and there’s speculation that some of the scrolls from the Great Library were used to stock them.
In 272 AD, the Emperor Aurelian fought to recapture the city from the Palmyrene queen Zenobia, and destroyed the Great Library’s section of the city in the process. If it was still standing then, it was certainly destroyed in the process. The 297 siege by Emperor Diocletian would’ve certainly destroyed the rest. Julius Caesar was not the (main) reason for the Library of Alexandria’s destruction.
Whatever the reason for destruction of the Great Alexandrian Library, the result was the irreplaceable loss of records of mankind’s recorded heritage up to that time. Destruction of the Great Libraries of Baghdad by Genghis Khan and episodes of bookburnings and murders of scholars and scientists since continue–as in the “Cultural Revolution” in China, the Cambodian genocide, destruction of Mayan, Aztec and Inca libraries and, of course, the Holocaust.
You would think humanity could do better than that.