The Book of Kells is usually described as the finest of the Insular gospel books, and the description is fair, but it can obscure what is strange about it. This is a gospel book in which the decoration does not accompany the text so much as consume it. On the Chi Rho page, the monogram that opens Matthew's account of the nativity expands until three letters occupy the whole leaf and disintegrate into spirals, interlace, animals, angels, and in one corner two cats watching mice steal a communion wafer. A reader looking for the sentence has to go hunting for it.
The pigments were expensive and were fetched from a long way off. The palette runs to orpiment, a poisonous arsenic sulphide that gives a gold-like yellow, verdigris, which has eaten through the vellum in places, and indigo. Several hands worked on the book, and they can be distinguished by how they handle a letter.
The Latin text, by contrast, is not good. It is a Vulgate crossed with older readings and copied with real carelessness, including at least one passage duplicated. That combination, a text treated casually and a decorative scheme treated as though nothing mattered more, tells you what the object was. It was not a study copy. It was made to be carried, displayed and venerated, and the Annals of Ulster describe it as a relic rather than as a book.