It happened that the art of Byzantium was in its prime just about the same time that vellum began to be arranged in sections--in book form--in contradistinction to the roll form. So we find some of the finest examples of Byzantine art on bookbindings. Of course it must be understood that these richly worked covers are only ornamentally added to the true binding underneath, and the actual work of the binding is more or less as I have already described it. But the decorative art in these cases is so predominant that they are generically known as “Byzantine” bindings. [Illustration: FIG. 47.--German binding of about the eleventh century, with cabochon crystals.] The large majority of the known specimens of this kind are no longer in company with their original manuscripts. Many of them are preserved simply as loose covers, and alien manuscripts have been inserted in others. I expect that there are still considerable numbers of these bindings preserved in remote churches and monasteries in Central Europe, and some day perhaps some traveller with sufficient knowledge and time at his command will make search for them. But for the present fine and genuine examples of Byzantine bindings are of great rarity. It is said that there are not more than about three hundred of them known. The life history of many of these is well known, and so are many of the additions and alterations to which they have been subjected during their long life. Luckily some of the finest are now safely housed in our London museums, and others are, or are likely to be, safe in a great local museum. To be able to judge whether these bindings are genuine, a librarian must be an antiquary, a goldsmith and silversmith, skilled both in repoussé work, engraving and cast work, a gem cutter, an enameller, a skilled bookbinder, and an artist, and if he fails in one of these knowledges his judgment cannot be relied on. An ordinary art critic who possesses “Flaire” can pick up a certain amount of knowledge by reason of having made many mistakes and profited by them, and if he has been fortunately able to associate himself only with true and known fine examples for a long time, he may eventually be a good guesser. But no true judgment can be given without actual technical knowledge. [Illustration: FIG. 48.--French binding of the thirteenth century with enamels.]