The Library of Alexandria was one of the largest and most significant libraries of the ancient world and part of a larger research institution called the Mouseion. Despite the widespread modern myth that the library was "burned" once and cataclysmically destroyed, the library actually declined gradually over the course of roughly 800 years, starting with the purging of intellectuals from Alexandria in 145 BC during the reign of Ptolemy VIII Physcon, which resulted in Aristarchus of Samothrace, the last recorded head librarian, resigning from his position and exiling himself to Cyprus. The library was accidentally burned by Julius Caesar during his civil war in 48 BC, but it is unclear how much of the library was actually destroyed and it may have been rebuilt shortly thereafter.
The library's membership appears to have ceased by the 260s AD and, between 270–275 AD, it was attacked under the orders of the emperor Aurelian, but, by that time, the center of learning in Alexandria had already been moved to the Serapeum. Theon of Alexandria and later his daughter Hypatia were heads of a school in Alexandria called the "Mouseion", which took its name from the Hellenistic institution that had once incorporated the library, but which had little other connection. The Serapeum was burned in 391 AD under a decree issued by Coptic Christian pope Theophilus of Alexandria, but it does not seem to have housed books at the time and was mainly used as a gathering place for Neoplatonist philosophers following the teachings of Iamblichus. Theophilus tolerated the school of Hypatia, but her school fell apart after her death in March of 415 AD. Some later legends ascribe the destruction of the Library of Alexandria to the Arabs in or after 642 AD, but there is little evidence to substantiate that there was even a library in Alexandria at the time.
The ancient accounts by Plutarch, Aulus Gellius, Ammianus Marcellinus, and Orosius indicate that troops of Caesar accidentally burned the library down during or after the Siege of Alexandria in 48 BC.
when the enemy endeavored to cut off his communication by sea, he was forced to divert that danger by setting fire to his own ships, which, after burning the docks, thence spread on and destroyed the great library.— Plutarch, Life of Caesar
However, the editor of Plutarch's translation notes that the "destruction of the Library can have been only partial", and that it occurred specifically in the Museum built by the first Ptolemy (283 BCE).
In the 2nd century AD, the Roman historian Aulus Gellius wrote in his book Attic Nights that the Library was burned by mistake after the siege when some of Caesar’s auxiliary soldiers started a fire. Aulus's translator similarly notes that, although auxiliary forces accidentally burned many books while stationed in Alexandria: "By no means all of the Alexandrian Library was destroyed [in 48 BC] and the losses were made good, at least in part, by Antony in 41 BC. A part of the library was burned under Aurelian, in AD 272, and the destruction seems to have been completed in 391."
William Cherf argued that this scenario had all the ingredients of a firestorm which set fire to the docks and then the library, destroying it. This would have occurred in 48 BC, during the fighting between Caesar and Ptolemy XIII. Furthermore, in the 4th century, both the pagan historian Ammianus and the Christian historian Orosius wrote that the Bibliotheca Alexandrina had been destroyed by Caesar's fire. The anonymous author of the Alexandrian Wars wrote that the fires set by Caesar's soldiers to burn the Egyptian navy in the port also burned a store full of papyri located near the port. However, a geographical study of the location of the historical Bibliotheca Alexandrina in the neighborhood of Bruchion suggests that this store cannot have been the Great Library.
Whether the burned books were only some stored books or books found inside the library itself, the Roman stoic philosopher Seneca (c. 4 BC – AD 65) refers to 40,000 books having been burnt at Alexandria. During his reign of the eastern part of the Empire (40–30 BC), Mark Antony plundered the second largest library in the world (at Pergamon) and presented the collection as a gift to Cleopatra as a replacement for the books lost to Caesar's fire.
Theodore Vrettos describes the damage caused by the fire: "The Roman galleys carrying the Thirty-Seventh Legion from Asia Minor had now reached the Egyptian coast, but because of contrary winds, they were unable to proceed toward Alexandria. At anchor in the harbor off Lochias, the Egyptian fleet posed an additional problem for the Roman ships. However, in a surprise attack, Caesar's soldiers set fire to the Egyptian ships resulting in the flames spreading rapidly and consuming most of the dockyard, including many structures near the palace. This fire resulted in the burning of several thousand books that were housed in one of the buildings. From this incident, historians mistakenly assumed that the Great Library of Alexandria had been destroyed, but the Library was nowhere near the docks... The most immediate damage occurred in the area around the docks, in shipyards, arsenals, and warehouses in which grain and books were stored. Some 40,000 book scrolls were destroyed in the fire. Not at all connected with the Great Library, they were account books and ledgers containing records of Alexandria's export goods bound for Rome and other cities throughout the world."
The Royal Alexandrian Library was not the only library located in the city. Down through Queen Cleopatra of the first century BCE, the Ptolemaic dynasty, stimulated Alexandria's libraries to flourish. There were at least two other libraries in Alexandria: the library of the Serapeum temple and the library of the Cesarion Temple. The continuity of literary and scientific life in Alexandria after the destruction of the Royal Library, as well as the city's status as the world’s center for sciences and literature between the 1st and the 6th centuries AD, depended to a large extent on the presence of these two libraries. Historical records indicate that the Royal Library was private (used by the royal family as well as scientists and researchers), but the libraries of the Serapeum and Cesarion temples were public and accessible to the people.
Furthermore, while the Royal Library was founded by Ptolemy II in the royal quarters of Bruchion near the palaces and the royal gardens, it was his son Ptolemy III who founded the Serapeum temple and its adjoined "Daughter" Library in the popular quarters of Rhakotis.
The next account is from Strabo's Geographica in 28 BC, which does not mention the library specifically, but does mention that he could not find a city map which he had seen when on an earlier trip to Alexandria, before the fire. Abaddi uses this account to infer that the library was destroyed to its foundations.
The accuracy of this account is suspect. The adjacent Museum was, according to the same account, fully functional, even though the building next door was completely destroyed. Also, we do know that at this time the daughter Library at the Serapeum was thriving and untouched by the fire. Strabo also confirms the existence of the "Museum." But when he mentions the Sarapeum and Museum, Strabo and other historians are inconsistent in their descriptions of the entire compound or the specific temple buildings. So we may not infer that the library arm had been demolished. Strabo was one of the world's leading geographers, but it is possible that since his last visit to the library, the map he was referencing (quite possibly a rare or esoteric map considering his expertise and the vast collection of the library) might have been part of the library that was partially destroyed or simply a victim of a library that didn't have the funds to recopy and preserve its collection.
Therefore, the Royal Alexandrian Library may have been burned after Strabo's visit to the city (25 BC) but before the beginning of the 2nd century AD when Plutarch wrote. Otherwise Plutarch and later historians would not have mentioned the incident and mistakenly attributed it to Julius Caesar. It is also most probable that the library was destroyed by someone other than Caesar, although the later generations linked the fire that took place in Alexandria during Caesar's time to the burning of the Bibliotheca. Some researchers believe it most likely that the destruction accompanied the wars between Queen Zenobia and the Roman Emperor Aurelian, in the second half of the 3rd century (see below).
The Mouseion continued as an institution in the Roman period when Strabo gave his description of it, and according to Suetonius, the emperor Claudius added an additional building. Under the emperors, membership of the Mouseion was awarded to prominent scholars and statesmen, often as a reward to supporters of the emperor. Emperor Caracalla suppressed the Mouseion in 216, perhaps as a temporary measure. By this time, the center of learning in Alexandria had already moved to the Serapeum. The last references to membership in the Mouseion date to the 260s AD.
The library itself seems to have been maintained and continued in existence until its contents were largely lost during the taking of the city by the Emperor Aurelian (270–275), who was suppressing a revolt by Queen Zenobia of Palmyra (ruled Egypt AD 269–274). During the course of the fighting, the areas of the city in which the main library was located were damaged. The smaller library located at the Serapeum survived, but some of its contents may have been taken to Constantinople during the 4th century to adorn the new capital. However, Ammianus Marcellinus, writing around AD 378, seems to speak of the library in the Serapeum temple as a thing of the past and states that many of the Serapeum library's volumes were burnt when Caesar sacked Alexandria. In Book 22.16.12–13, he says:
Besides this there are many lofty temples, and especially one to Serapis, which, although no words can adequately describe it, we may yet say, from its splendid halls supported by pillars, and its beautiful statues and other embellishments, is so superbly decorated, that next to the Capitol, of which the ever-venerable Rome boasts, the whole world has nothing worthier of admiration. In it were libraries of inestimable value; and the concurrent testimony of ancient records affirm that 70,000 volumes, which had been collected by the anxious care of the Ptolemies, were burnt in the Alexandrian war when the city was sacked in the time of Caesar the Dictator.
While Ammianus Marcellinus may be simply reiterating Plutarch's tradition about Caesar's destruction of the library, it is possible that his statement reflects his own empirical knowledge that the Serapeum library collection had either been seriously depleted or was no longer in existence.
Two main varieties of Neoplatonism were taught in Alexandria during the late fourth century AD. The first was the overtly pagan religious Neoplatonism taught at the Serapeum, which was greatly influenced by the teachings of Iamblichus. The second variety was the more tolerant, intellectual, and less explicitly pagan variety championed by Hypatia and her father Theon, which was based on the teachings of Plotinus. Although Hypatia herself was a pagan, she was tolerant of Christians. In fact, every one of her known students was Christian. One of her most prominent pupils was Synesius of Cyrene, who went on to become a bishop of Ptolemais (now in eastern Libya) in 410.
Socrates of Constantinople provides the following account of the destruction of the temples in Alexandria, in the fifth book of his Historia Ecclesiastica, written around 440:
At the solicitation of Theophilus, Bishop of Alexandria, the emperor issued an order at this time for the demolition of the heathen temples in that city; commanding also that it should be put in execution under the direction of Theophilus. Seizing this opportunity, Theophilus exerted himself to the utmost to expose the pagan mysteries to contempt. And to begin with, he caused the Mithraeum to be cleaned out, and exhibited to public view the tokens of its bloody mysteries. Then he destroyed the Serapeum, and the bloody rites of the Mithreum he publicly caricatured; the Serapeum also he showed full of extravagant superstitions, and he had the phalli of Priapus carried through the midst of the forum. [...] Thus this disturbance having been terminated, the governor of Alexandria, and the commander-in-chief of the troops in Egypt, assisted Theophilus in demolishing the heathen temples.
The Serapeum had housed part of the Great Library, but it is not known how many, if any, books were contained in it at the time of destruction. Notably, the passage by Socrates makes no clear reference to a library or its contents, only to religious objects. An earlier text by the historian Ammianus Marcellinus indicates that the library was destroyed in the time of Julius Caesar; whatever books might earlier have been housed at the Serapeum were no longer there in the last decade of the 4th century (Historia 22, 16, 12-13). The pagan scholar Eunapius of Sardis, witnessed the demolition, and though he detested Christians, his account of the Serapeum's destruction makes no mention of any library. When Orosius discusses the destruction of the Great Library at the time of Caesar in the sixth book of his History against the Pagans, he writes:
So perished that marvelous monument of the literary activity of our ancestors, who had gathered together so many great works of brilliant geniuses. In regard to this, however true it may be that in some of the temples there remain up to the present time book chests, which we ourselves have seen, and that, as we are told, these were emptied by our own men in our own day when these temples were plundered—this statement is true enough—yet it seems fairer to suppose that other collections had later been formed to rival the ancient love of literature, and not that there had once been another library which had books separate from the four hundred thousand volumes mentioned, and for that reason had escaped destruction.
Thus Orosius laments the pillaging of libraries within temples in 'his own time' by 'his own men' and compares it to the destruction of the Great Library destroyed at the time of Julius Caesar. He is certainly referring to the plundering of pagan temples during his lifetime, but this presumably did not include the library of Alexandria, which he assumes was destroyed in Caesar's time. While he admits that the accusations of plundering books are “true enough,” he then suggests that the books in question were not copies of those that had been housed at the Great Library, but rather new books "to rival the ancient love of literature." Orosius does not say where temples' books were taken, whether to Constantinople or to local monastic libraries or elsewhere, and he does not say that the books were destroyed.
Theon of Alexandria was the head of a school called the "Mouseion", which was named in emulation of the Hellenistic Mouseion that had once included the Library of Alexandria. Theon's school was exclusive, highly prestigious, and doctrinally conservative. Theon rejected the teachings of Iamblichus and may have taken pride in teaching a pure, Plotinian Neoplatonism. In around 400 AD, Theon's daughter Hypatia succeeded him as the head of his school.
Theophilus, the same bishop who ordered the burning of the Serapeum, tolerated Hypatia's school and encouraged two of her students to become bishops in territory under his authority. Hypatia was extremely popular with the people of Alexandria and exerted profound political influence. Theophilus respected Alexandria's political structures and raised no objection to the close ties Hypatia established with Roman prefects. Hypatia was later implicated in a political feud between Orestes, the Roman prefect of Alexandria, and Cyril of Alexandria, Theophilus's successor as bishop. Rumors spread accusing her of preventing Orestes from reconciling with Cyril and, in March of 415 AD, she was murdered by a mob of monks under Cyril's authority known as the parabalani, led by a lector named Peter. He had no successor and her school collapsed after her death.
In AD 642, Alexandria was captured by the Muslim army of 'Amr ibn al-'As. There are four Arabic sources, all at least 500 years after the supposed events, which mention the fate of the library.
The story was still in circulation among Copts in Egypt in the 1920s.
Bernard Lewis has observed that this version was reinforced in medieval times by Saladin, who decided to break up the Fatimid Caliphate's collection of heretical Isma'ilism texts in Cairo following his restoration of Sunni Islam to Egypt, and will have judged that the story of the Caliph Umar's support of a library's destruction would make his own actions seem more acceptable. Roy MacLeod
Luciano Canfora included the account of Bar Hebraeus in his discussion of the destruction of the library without dismissing it.