With the development of printing, the need of methods of multiplying illustrations for printed books soon made itself felt and was finely responded to by the genius of the century. Wood-engraving in the service of book-illustration came in very early in the history of printing and was, after all, only a development of the wooden blocks, out of which the first idea of movable types had originally sprung. It was very crude at the beginning, and yet often with an artistic expression that gives it great interest. Its possibilities for printing in company with movable types soon began to be realized, and as printed books became more beautiful and type faces more artistic, the necessity for supplying artistic illustrations was felt, and then it was not long before the need was supplied. Probably the {159} first wood-engraving designed for book-illustration which exhibits a marked artistic quality was "The Dream of Poliphilo," in which, as Woodberry says in his "History of Wood-Engraving," "Italian wood-engraving, quickened by the spirit of the Renaissance, displayed its most beautiful creation." It was written by a Venetian monk, Francesco Colombo, in 1467, and was first printed by Aldus in 1499. The subject was a worthy one, for though the book is a strange mingling of Greek, Latin, Hebrew and Arabic traditions and poetic symbolism, it typifies the spirit of the Renaissance. It represents the search of youth for the loveliness of universal nature and the perfection of ancient art under the title of Polia, the charming maiden who combines all the qualities. Altogether there are 192 designs. They have been attributed to many illustrious masters, even John Bellini and Raphael, among others, but were probably due to Benedetto Montagna. How soon illustration came to aid in the understanding of the text in books is very well illustrated by Fra Giocondo's work. When, in 1508, he published the letters of the younger Pliny in the Aldine edition, he not only described but illustrated the villas of the ancients. In 1511 he edited the Aldine edition of Vitruvius, with its rude woodcuts that are yet much more thoroughly illustrative than many a more ambitious modern book and which include the first modern plan of a Roman house. When he issued his Aldine edition of Caesar in 1513 this was illustrated with the earliest of all modern drawings of Caesar's bridge across the Rhine. Fra Giocondo is in fact the true father of the illustrated classic, as Sandys suggested in his Harvard Lectures on the "Revival of Learning" (Cambridge University Press, 1905). It may be well to add that the good friar was no mere student for erudition's sake, since, as is noted in the chapter on architecture, he entered the royal service in France, and in 1497 designed one at least, if not two, of the noble bridges that still span the Seine.