For this reason the _Abecedarium_ has been claimed by the Dutch historians of typography as the first production of the inventor of the art. They say that it was printed before any edition of the _Speculum_, and probably in the first quarter of the fifteenth century. A closer [p291] examination of the book does not lead to this conclusion: the printer of the book was, no doubt, a careless workman, but he had been taught the trade. The fragments of the tract are in four pieces, but they were printed in one form of eight pages, and by one impression. This artificial arrangement of the pages, in the arbitrary position which allows them to be folded together in regular order, reveals an expertness in little technicalities on the part of this early printer which is somewhat unexpected. The method of printing sheets imposed in forms of eight pages was not in fashion before it was adopted by Aldus Manutius, of Venice, in his edition of Virgil dated 1501. It is not an invention of the first, but of the last quarter of the fifteenth century, to which period this book belongs.[148] The types of the book were not set up by an experimenter or ignoramus. The comparatively even outline to the right of every page shows that the compositor tried to space out his lines and to give every page an appearance of uniform squareness. As full and even-spaced lines are not to be found in any edition of the _Speculum_, nor in any of the first books of the early printers, we may conclude that the _Abecedarium_ was printed at a later date, when this improvement had been adopted by all printers. It has been maintained that the book must be very old, because it is printed on one side only, after the fashion of the block-printers. This is an improper inference, for each fragment has the appearance of a spoiled impression which was rejected before the sheet had been perfected by printing on the other side. The unfilled space for the initial letter shows that the work on the sheet was never completed. [p292]