The aim of this paper is to prove how what is apparently a mistake made by Plutarch, wheter deliberate or not, in his reference to the arson attack of Caesar´s soldiers in Alexandria as the end of the famous Library, show us the common sense of the term “bibliotheke” from that time up to now. Coming to this conclusion has required a detailed analysis of the Library of Alexandria since its birth applying Aristotelian doctrine to its configuration not only as (...) an organized space for books but also as an imaginary reading room from which the helenistic world of relations is established. In a second approach, we focus the attention on the change occurred in this collection with the introduction of alphabetical order and, then, with the philological activity of Callimachus. As a result of his Pinakes, the platonic concept of daimon, “guide”, became the first characteristic o a philologist or librarian. Using the information ordered in the Pinakes anybody could be a librarian and find a library anywhere. The old megále bibliotheke of Alexandría remains only with the idea of the conservation of original papyrus. This is de reason of the enigmatic sentence of Plutarch announcing the end of this situation caused by the action of the fire. (shrink)