With the block-books, the essential thing was the illustrations, and what text or letterpress accompanied these was usually limited to a few explanatory or descriptive words engraved on the block, above, beneath or around the picture. Occasionally, however, as in the _Ars Moriendi_, there were entire pages of text engraved, like the designs, on the solid block. The earlier engraving was done on hard wood, but, later, copper was also employed. It is probable that the block-books originated in the Netherlands, and it is certain that in such towns as Bruges, Antwerp, and Amsterdam, the art was developed more rapidly than elsewhere, so that during the first half of the fifteenth century, the production of wood engravings and of books made up of engravings (printed only on one side, and accompanied by a few words of text), began to form an important article of trade. The subjects of these designs were for the most part Biblical, or at least religious. One of the earlier of the block-book publications and probably the most characteristic specimen of the class, is the volume known as the _Biblia Pauperum_. This was a close imitation of a manuscript book that had for five or six centuries been popular as a work of religious instruction. It had been composed about 850, by S. Ausgarius, a monk of Corbie, who afterwards became Bishop of Hamburg. The _scriptorium_ established by him at Corbie was said to have been the means of preserving from destruction a number of classics, including the _Annals_ of Tacitus.[422] The use, five centuries later, as one of the first productions of the printing-press, of the monk’s own composition, may be considered as a fitting acknowledgement of the service thus rendered by him to the world’s literature. Examples of manuscript copies of the _Biblia Pauperum_ are in existence in the _Bibliothèque Nationale_ in Paris, in Munich, in the British Museum, and elsewhere, and there is no difficulty in comparing these with the printed copies produced in the Netherlands, which are also represented in these collections. It is probable that Laurence Koster of Haarlem, whose name is, later, associated with printing from movable type, was himself an engraver of block-books. Humphreys is, in fact, inclined to believe that the first block-book edition of the _Biblia Pauperum_ was actually Koster’s work, basing this opinion on the similarity of the compositions and of their arrangement to those of the _Speculum Humanæ Salvationis_, which was the first work printed from movable type, and the production of which is now generally credited to Koster.[423] The _Biblia Pauperum_ was printed from blocks in Germany as late as 1475, but before that date an edition had been printed from movable type by Pfister in Bamberg.