quality:corruption
Collection

It is not possible to determine the collection's size in any era with certainty. Papyrus scrolls constituted the collection, and although codices were used after 300 BC, the Alexandrian Library is never documented as having switched to parchment, perhaps because of its strong links to the papyrus trade. The Library of Alexandria in fact was indirectly causal in the creation of writing on parchment, as the Egyptians refused to export papyrus to their competitor in the Library of Pergamum. Consequently, the Library of Pergamum developed parchment as its own writing material.

A single piece of writing might occupy several scrolls, and this division into self-contained "books" was a major aspect of editorial work. King Ptolemy II Philadelphus (309–246 BC) is said to have set 500,000 scrolls as an objective for the library. The library's index, Callimachus ' Pinakes, has only survived in the form of a few fragments, and it is not possible to know with certainty how large and how diverse the collection may have been. At its height, the library was said to possess nearly half a million scrolls, and, although historians debate the precise number, the highest estimates claim 400,000 scrolls while the most conservative estimates are as low as 40,000, which is still an enormous collection that required vast storage space.

As a research institution, the library filled its stacks with new works in mathematics, astronomy, physics, natural sciences, and other subjects. Its empirical standards were applied in one of the first and certainly strongest homes for serious textual criticism. As the same text often existed in several different versions, comparative textual criticism was crucial for ensuring their veracity. Once ascertained, canonical copies would then be made for scholars, royalty, and wealthy bibliophiles all over the world, this commerce bringing income to the library.