During the first half of the fifteenth century, in more than one quarter of Europe, ingenious minds were at work seeking by various experiments and repeated trials, with more and more success, the great invention of printing with movable types; even now, after the most searching inquiry, the time and place of the invention are uncertain. Printing with movable types, however, was preceded and suggested by printing from engraved wood-blocks. The holy prints sometimes bore the name of the saint, or a brief _Ora pro nobis_ or other legend impressed upon the paper; the wood-engravers who first cut these few letters upon the block, although ignorant of the vast consequences of their humble work, began that great movement which was to change the face of civilization. After letters had once been printed, to multiply the words and lengthen the sentences, to remove them from the field of the cut to the space below it, to engrave whole columns of text, and, finally, to reproduce entire manuscripts, and thus make printed books, were merely questions of manual skill and patience. Where or when or by whom these block-books, as they are called, were first engraved and printed is unknown; these questions have been bones of contention among antiquarians for three hundred years, and in the dispute much patient research has been expended, and much dusty knowledge heaped together, only to perplex doubt still farther, and to multiply baseless conjectures. It is probable that they were produced in the first half of the fifteenth century, when the men of the Renaissance, whose aroused curiosity made them alert to seize any new suggestion, were everywhere seeking for means to overthrow the great barrier to popular civilization, the rarity of the instruments for intellectual instruction; they soon saw of what service the new art might be in this task, through the cheapness and rapidity of its processes, and they applied it to the printing of words as well as of pictures.