Compare this page with the reproductions of the Mazarin, or forty-two line Bible, shown on pages 48 and 49. We know that the Mazarin Bible was printed not later than 1456. By some it has been attributed to Gutenberg, or at least to his types, but it is now considered the work of Schoeffer. The Mazarin Bible is one of the most perfect and splendid pieces of typography that has ever been produced. Other work attributed to Gutenberg shows a high degree of excellence. It has always been one of the wonders of invention that so difficult and complicated an art as typography should have sprung into being fully perfected, without trace of imperfect experiment. In the rough page of Coster’s Donatus we clearly see the imperfect beginning—the missing link. These peculiarities are exactly what we should expect to find in the missing links between the printing of block books and the printing of books from type. The printer is experimenting. He cuts the lettering off his blocks and combines them with type. He uses type and blocks for the same edition. He experiments with paper. He is very primitive in his methods. A block book could be printed only on one side. He is not yet sure that the type-set book can be printed on both sides. Not improbably he began by using for his type page the same method of printing that he used with his wooden block. It seems pretty clear that in this mass of material, known collectively as the Costeriana, we have the records of the course of experimentation which led from the printing of the image print, with its legend cut on the same block, by placing a sheet of paper or vellum on the inked surface of the block and pressing it down with a frotten, to the production of the book from type-set pages impressed upon both sides of the paper by means of a press. We have thus gone through the evidence of the first class which exists for the invention of printing. We have seen that there exists indisputable evidence that forty-seven editions were printed at Haarlem before 1474 by an experimenter who seems to have gone over the road from the block book to the type-set book. [Illustration: Reduced Facsimile of Type Page by Coster.] [Illustration: Reduced Facsimile of Block Printing]