The present day is notably distinguished by the prevalence of enormous numbers of printed books, periodicals, and newspapers. Yet this very printing, which seems so commonplace to us now, has had, in all, but a comparatively brief existence. From the earliest recorded history up to less than five hundred years ago every book in Europe [Footnote: For an account of early printing in China, Japan, and Korea, see the informing article "Typography" in the _Encyclopædia Britannica_, 11th edition, Vol. XXVII, p. 510.] was laboriously written by hand, [Footnote: It is interesting to note the meaning of our present word "manuscript," which is derived from the Latin--_manu scriptum_ ("written by hand").] and, although copyists acquired an astonishing swiftness in reproducing books, libraries of any size were the property exclusively of rich institutions or wealthy individuals. It was at the beginning of modern times that the invention of printing revolutionized intellectual history. Printing is an extremely complicated process, and it is small wonder that centuries of human progress elapsed before its invention was complete. Among the most essential elements of the perfected process are _movable type_ with which the impression is made, and _paper_, on which it is made. A few facts may be conveniently culled from the long involved story of the development of each of these elements. [Sidenote: Development of paper] For their manuscripts the Greeks and Romans had used papyrus, the prepared fiber of a tough reed which grew in the valley of the Nile River. This papyrus was very expensive and heavy, and not at all suitable for printing. Parchment, the dressed skins of certain animals, especially sheep, which became the standard material for the hand- written documents of the middle ages, was extremely durable, but like papyrus, it was costly, unwieldy, and ill adapted for printing.