Some of these books were printed in many editions and had enormous circulation. At a later period a few lines of explanatory text were added to the picture. In some cases these lines were part of the plate. In other cases they were written and in some they were even printed, as the use of the block book survived the invention of typographical printing. These block books were exactly like the picture books which we now place in the hands of little children. They were to be looked at rather than read. The meager explanatory text, as in the case of the child's book, served the double purpose of a simple reading lesson and of an aid to the explanation of the book for the benefit of the owner by some wiser person. One of the most popular of these books was the Biblia Pauperum, or Poor Man's Bible. This contained a large number of pictures covering the more striking incidents of the biblical story. These were not arranged in any particular order, as the idea of historical study of the scriptures had not yet made its appearance. A sample page for instance, shows an architectural design. The larger part of the page is occupied by three panels. Above and below the middle panel are two smaller ones leaving four blank rectangles at the corners of the page. The middle one of the larger panels shows Jesus rising from the tomb while the other two show Samson carrying away the gates of Gaza and Jonah being disgorged by the whale. Each of the two smaller panels at top and bottom is occupied by two figures, the four being intended to represent David, Jacob, Hosea, and Zephaniah. Fortunately the "portraits" are labelled as these biblical worthies are represented in the ordinary costume of well-to-do citizens of the early part of the 15th century. [Illustration: Page from the second edition of the Poor Man's Bible, about 1450.] This and other block books continued to be reprinted in type after the invention of typography. One block book and one only, so far as is known, was without pictures. This was a Latin grammar commonly known as Donatus, from its author the famous Roman grammarian Donatus of the 4th century. This was the one Latin grammar in use in the middle ages, when Latin was the foundation of all culture. It was, therefore, very extensively used and it is supposed that more copies were printed of it than of any other block book. It has the further distinction of being the only block book printed on vellum. Ordinarily the desire for cheapness and the much greater ease of handling the material caused the block books to be printed on paper. The importance of the Donatus as a book of reference and the hard usage it was likely to receive at the hands of schoolboys caused the use of the more expensive but more durable material.