One mechanical peculiarity of the block-books deserves a specific notice: all the block-books were printed on paper. The printers soon discovered that vellum was an intractable material, and they preferred paper as much for its convenience as for its cheapness. An apparent dislike of black ink is equally noticeable; the color in different books varies from a blackish gray to a dingy brown. But their most characteristic feature is the method of printing upon one side of the sheet. One chronicler says that the leaves were so printed that the blank sides might be pasted together. That this is not the true reason is apparent when we discover that very few of the books have pasted leaves. It is more reasonable to suppose that the earlier block-printers could not print on both sides of the paper. It is plain that they could not produce a neat impression even on one side—could not regulate the force of the impression, which was so harsh and violent that it sometimes spread the ink, and deeply indented the paper. As the margins are uneven, we have to infer that the printers could not place the sheets with uniform accuracy upon the blocks. Consequently, they could not print in register, and place the second page truly on the back of the first. Some authorities say that the paper was printed dry, but this is only a conjecture, made to suit the theory of printing by the frotton. The paper must have been dampened, for it was very thick, and as strong and as coarse as modern manila wrapping; it could not have been legibly printed until it had been softened. With few exceptions, the block-books are of a religious character; but the religion taught is dogmatic and doctrinal more than devotional. We may safely assume that they were written by ecclesiastics in high station for the instruction of the ignorant monks, mendicant friars, and “unable curates.” [p249] Illiterate priests, to whom the descriptions or the legends of the pictures had been read, must have understood their historical and spiritual meaning, and must have found the pictures an aid to the memory, and suggestive of topics for preaching. Although made for priests, they were not beyond the reach of the people. As far back as the twelfth century, an English abbot sternly forbade, under penalty of excommunication, the lending of any books, “neither the large books with pictures, nor the small books without pictures.” But the mandate was disregarded. Sooner or later, the books found their way to the hands of laymen, whose ignorance of Latin did not prevent them from admiring the pictures; and this admiration must have inspired many a reader with the desire to learn the strange language and to own the coveted book.