Parchment, which is the prepared skins of animals, came into use B. C. 250. It was so called from Pergamus (_membrana pergamea_), whose king, Eumenes, seeking to collect a library which should vie with that of Alexandria, and being debarred a supply of papyrus by the jealousy of the Ptolemies, had recourse to this substitute. After the eighth century, parchment generally took the place of papyrus. Ancient books were not commonly disposed in a square form, as with us, but were _rolled_ up. Hence the word _volume_, signifying a roll. Paper from cotton and linen rags began, it is thought, to be made as early as the ninth century. For several centuries, however, the manufacture was so scanty as to increase very little the facilities for copying. Gradually, it became more plentiful, and writing material of small cost laid the foundation for that cheap and expeditious mode of copying which we call printing. In the age when parchment was used, it was often difficult to be obtained; and it became common to erase the original writing from a manuscript and trace another upon it. A parchment thus used was called _palimpsest_, which means “twice prepared for writing.” Thus, many valuable works were destroyed to make way for newer, and, in some cases, less important ones. Happily we live in a time when we have no occasion to destroy one library to produce another. It seems strange, too, that a transcriber familiar with the labor of copying would not be deterred by his love of learning from putting even one book out of existence. But necessity knew no law; and the writer, deeming his own work to possess greater utility, sacrificed another to make room for it,--to such straits were the scribes sometimes brought for the lack of writing material. Struggling to express thought, there was no room to put it down. Written language, scarcely second to spoken language, had almost perished; and had the art of printing been invented before paper was known, it would have been comparatively useless. The writing and rewriting on parchment, as it was often done two or three times, has recently led learned men to make these ancient parchments a study; and they have thus deciphered or read the last writing, then, effacing that, have deciphered the second, and, effacing that, have read the first,--often the most valuable,--and in this way have brought to light lost works, and found out many important facts of history.