There is something specially terrible about the deliberate destruction of books. Chesterton once said that we say that a man is acting like an animal when what we mean is that he is acting like a man: animals do what they do, whatever its effects, because they see no choice, but people do evil on purpose. I can still remember the shock I felt when I first read Evelyn Waugh's Vile Bodies, opening with the destruction by officious customs officers of the manuscript of a novel.
One of the clearest signs of a regime that has lost its footing in reality is when it starts to think burning books is a good idea. Even the Soviet Union, which was quite capable of burning people if it thought it helpful, would only lock books up and restrict access to the trusted few (well, not only do that: they would also lock up the writers and readers too, but the books they left). In the 1930s, anyone who was in any doubt as to the reasonableness and bidability of the Nazis should have reached a conclusion as the ashes settled. It takes a special sort of culture to believe that books as physical objects have such power that they must be erased. Not so special these days, alas.
The first and greatest loss was that of the Great Library of Alexandria. I know it, and you know it, but I was surprised to find when researching my poem The last librarian that while it is generally agreed that it as burnt down and that much knowledge was lost as a result, who did it, and when, is still open to question. You could see this as a sort of paradox: after all, where would the Book that Named the Culprit have been shelved when all shelves have gone? But it appears (to be brief) that there were a series of fires, probably starting with Julius Caesar in the 40sBC, another one in 395 AD, and another in the 650s, which neatly shares the blame between Romans, Christians and Muslims (the latter two on purpose). Hypatia (who I call the Last Librarian in the poem although she wasn't in fact in charge of the library: her father was) was an astronomer and mathematician who was (so the story goes) killed a few years after the Christian torching of the library at the behest of Cyril the Patriach of Alexandria.