These block-books, or xylographica, of which up-
wards of a hundred issues and editions, comprising
some thirty separate works, have been recorded, were
produced chiefly in the Netherlands and Germany. They
fall into two classes. The earlier were printed in thin
pale brownish ink on one side of the leaf only. They were
produced by placing a sheet of paper upon the inked
block and transferring the image to the paper by fric-
tion on the back of the sheet with a burnisher or some
similar instrument, without mechanical pressure. The
other and later class were usually printed in a press
with ordinary black printing ink and on both sides of
the paper.

Since the contents of each individual page had to be
engraved upon a block of wood, the making of a block-
book was a laborious process, and one suitable only for
works of moderate length for which there was a large
and continuous demand. These books were, accordingly,
of a popular nature, mainly concerned with religious in-
struction or pious edification, and lending themselves
readily to pictorial or allegorical illustration. Typical
examples are the Biblia Pauperum, a series of pictures
from the life of Christ, accompanied by parallel subjects
from the Old Testament; the Apocalypse, an attractive
subject for illustrations; and Ars Moriendi, a series of
pictures representing the trials which beset the dying
and the spiritual helps by which they may be overcome.

While this method of reproduction was fairly con-
venient for the class of work for which it was used, it
was quite inadequate to the cheap and speedy multiplica-
tion of that type of book which the revival of literature
and learning was demanding.

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