In the musters, or processions, of the University of Paris, the bookbinders came after the booksellers. To explain the relatively small number of professed bookbinders, we must remember that at this period the majority of scholars bound their own books, as divers passages of ancient authors prove; while the monasteries, which were the principal centres of bookmakers, had one or many members of their community whose special function it was to bind the works written within their walls. Tritheimius, Abbot of Spanheim at the end of the fifteenth century, does not forget the bookbinders in the enumeration he makes of the different employments of his monks:--“Let that one,” says he, “fasten the leaves together, and bind the book with boards. You, prepare those boards; you, dress the leather; you, the metal plates, which are to adorn the binding.” These bindings are represented on the seal of the University of Oxford (Fig. 381), and on the banners of some French corporation of printers and booksellers (Figs. 382 and 386). The metal plates, the corners, the nails, the clasps with which these volumes were then laden rendered them so heavy that, in order to enable the reader to turn over the leaves with facility, they were placed on one of those revolving desks having space for many open folios at the same time, and which were capable of accommodating many readers simultaneously. It is said that Petrarch had caused a volume containing the “Epistles of Cicero,” transcribed by himself, to be bound so massively, that as he was continually reading it, he often let it fall and injured his leg; so badly once that he was threatened with amputation. This manuscript in Petrarch’s handwriting is still to be seen in the Laurentian Library at Florence; it is bound in wood, with edges and clasps of copper. The Crusades, which introduced into Europe many luxurious customs, must have had great influence on bookbinding, since the Arabs had for a long while known the art of preparing, dyeing, stamping, and gilding the skins they employed to make covers for books: these covers took the name of _alæ_ (the wings), no doubt from the resemblance between them and the wings of a bird of rich plumage. The Crusaders having brought back from their expeditions specimens of Oriental binding, our European workmen did not fail to turn their brilliant models to account. [Illustration: Fig. 381.--Seal of the University of Oxford, in which is a Book bound with Corners and Clasps.]