In recent years bibliographers have become more aware of the fact that a large number of early printed editions, in particular those belonging to the Fifteenth and early Sixteenth centuries, have been wholly lost. Although it is difficult to perform a precise calculation, the existence of a resource such as the “Incunabula Short Title Catalogue”, in which, in a total of 27,000 editions, 6,800 are known in a single, often imperfect, copy, allows a projection according to which the number of lost editions is in the order of 12,000 to 20,000. After a round-up of the previous bibliographical discussion and taking as its starting point the fact that the principal force that destroys books is use by readers, the article discusses a list of fifteen further factors, which, sometimes in contradictory fashion, play a part in the process, i.e. 1) external forces (fire, flood, etc.), 2) language, 3) size, 4) time, 5) genre, 6) censorship, 7) ephemera, 8) obsolescence, 9) importance of the publishing centre, 10) nature of the edition, 11) support, 12) print-run, 13) price, 14) distribution, 15) manner of conservation.
