Morgan Library in the context of "J. P. Morgan, Jr."

A treasure binding or jewelled bookbinding is a luxurious book cover using metalwork in gold or silver, jewels, or ivory, perhaps in addition to more usual bookbinding material for book covers such as leather, velvet, or other cloth. The actual bookbinding technique is the same as for other medieval books, with the folios, normally of vellum, stitched together and bound to wooden cover boards. The metal furnishings of the treasure binding are then fixed, normally by tacks, onto these boards. Treasure bindings appear to have existed from at least Late Antiquity, though there are no surviving examples from so early, and Early Medieval examples are very rare. They were less used by the end of the Middle Ages, but a few continued to be produced in the West even up to the present day, and many more in areas where Eastern Orthodoxy predominated. The bindings were mainly used on grand illuminated manuscripts, especially gospel books designed for the altar and use in church services, rather than study in the library.

The vast majority of these bookbindings were later destroyed as their valuable gold and jewels were removed by looters, or the owners when in need of cash. Others survive without their jewels, and many are either no longer attached to a book, or have been moved to a different book. Some survive in major libraries; for example, the Morgan Library in New York City, the John Rylands Library in Manchester, the British Library in London, the Bayerische Staatsbibliothek in Munich and the Bibliothèque Nationale in Paris. As the carved ivory reliefs often used could not usually be recycled, these survive in much larger numbers, giving a better idea of the numbers of treasure bindings that once existed. Other examples are recorded in documentary sources but though the books survive the covers do not. The Book of Kells lost its binding after a robbery, and the fate of the missing cover of the Book of Lindisfarne is not recorded.

The Lindau Gospels is an illuminated manuscript in the Morgan Library in New York, which is important for its illuminated text, but still more so for its treasure binding, or metalwork covers, which are of different periods. The oldest element of the book is what is now the back cover, which was probably produced in the later 8th century in modern Austria, but in the context of missionary settlements from Britain or Ireland, as the style is that of the Insular art of the British Isles. The upper cover is late Carolingian work of about 880, and the text of the gospel book itself was written and decorated at the Abbey of Saint Gall around the same time, or slightly later.

When J.P. Morgan, already in his early sixties, bought the book in 1901, it was his first major purchase of a medieval manuscript, setting the direction that much of his subsequent collecting was to follow.

A cross pattée or cross patty (French: croix pattée, German: Tatzenkreuz), also known as a cross formée or cross formy, or even a Templar cross, is a type of Christian cross with arms that are narrow at the centre and often flared in a curve or straight line shape to be broader at the perimeter. The form appears very early in medieval art, for example, in a metalwork treasure binding given to Monza Cathedral by Lombard queen Theodelinda (died 628) and the 8th-century lower cover of the Lindau Gospels in the Morgan Library. An early English example from the start of the age of heraldry proper (i.e., about 1200) is found in the arms of Baron Berkeley.