Block-books continued to be printed and reprinted, first in Holland and afterward in Germany, with considerable activity, for twenty or thirty years, during which period we had several editions of the _Biblia Pauperum_, the _Ars Moriendi_ (or _Art of Dying),_ the _Speculum Humanae Salvationis_, and many others, chiefly devoted to the promulgation of scripture history. The earliest ones are printed, or rather transferred by friction--and therefore on one side only of the paper--entirely from solid blocks; later on, some portions were printed with movable types of wood; and at last the letter-press was entirely of movable metal types. Junius says that Koster by degrees exchanged his wooden types for leaden ones, and these for pewter; and I will add that it is not unlikely they may have been cast in lead or pewter plates from the wooden blocks, as metal-casting was well understood at the time. The pretensions of Haarlem and Koster have for more than a century been a matter of fierce controversy; and there have been upward of one hundred and fifty volumes written for or against, without any approach to a satisfactory decision. This one thing is certain, that, whether or not we owe the first idea of movable type to Laurence Koster or to Haarlem, we do not owe to the period any very marked use of it; that was reserved for a later day. There is a story current, dependent on the authority of Junius, that Koster's principal workman, assumed to be Hans or John Faust--and some, to reconcile improbabilities, even say John Gutenberg--who had been sworn to secrecy, decamped one Christmas Eve, after the death of Koster, while the family were at church, taking with him types and printing apparatus and, after short sojourns at Amsterdam and Cologne, got to Mainz or Mayence with them, and there introduced printing. He is said by Junius to have printed, about the year 1442--that is, two years after Koster's death--the _Doctrinale_ of Alexander Gallus and the _Tracts_ of Peter of Spain, with the very types which Koster made use of in Haarlem; but as no volume of this kind has ever been discovered, nor any trace of one, the entire story is generally regarded as apocryphal. Laurence Koster died in 1440, at the age of seventy; therefore any printing attributed to him must be within that period. What has hitherto been advanced proves only that mankind had walked for many centuries on the borders of the two great inventions, chalcography and typography, without having fully and practically discovered either of them. We now come to the great epoch of printing--I mean the complete introduction, if not actually the first invention, of movable metal or fusile types. This took place at Mainz, in or before 1450, and the general consent of Europe assigns the credit of it to Gutenberg. Of a man who has conferred such vast obligations on all succeeding ages, it may be desirable to say a few words.