The Book of Kells, circa 800

It has been called the Irish equivalent of the Sistine Chapel, and the analogy is not ridiculous. The Book of Kells is not merely the greatest work of Irish visual art. It belongs among the great creations of western art.

One of the big differences, though, is that the Book of Kells is also funny and playful and combines its grand religious vision with a homely humanity. Everywhere there are touches of comedy: a letter extended to form a monk’s tonsure, a word broken in two by the paw of a cat.

This is not to say that the task of making the book was anything but serious. It required the skin of 185 calves to make the vellum pages. The range of pigments used for the colours – orpiment, vermilion, verdigris, woad and, perhaps, folium, which produces beautiful shades of mauve and purple – is far greater than that of other contemporary books. There may have been one guiding visionary leading the team of monks, as it is clear that on many pages the script and the images were done by the same hand.

There have been arguments over the years about where the book was made, with suggestions ranging from Spain to (more plausibly) the great monastery at Lindisfarne, in Northumbria. One place it was almost certainly not created is Kells itself. Instead, the consensus is that the book was made on the island of Iona, off the west coast of Scotland, whose heavily Irish monastery was founded by Saint Columcille in 561. It may well have been intended to honour his memory: from early on it was known as “the great book of Columcille”.

Iona was raided by Vikings in 802 and 806, and its monks retreated to a new base in Kells. The probability is that they brought at least the bulk of the book with them: it is not implausible that some subsequent work may have been done in this new monastery in Co Meath.

Whatever its precise history, the book can be securely placed within Irish culture. The contorted animals, highly stylised humans and fabulously ornate initial lettering are still rooted in the La Tène tradition of “Celtic” art that had been rooted in Ireland for 1,000 years. Many of the animal and bird images are indeed comparable to those of the great Irish metalworkers.

But, in a way that is also typically Irish, the book is fed by many cultural streams, from Pictish sculpture in Scotland to Visigothic and Carolingian design in Spain and France, and even to the Coptic art of the north African church.

Even the biblical text itself is eclectic, combining passages from different Latin translations. Indeed, it seems that the monks paid more attention to the sumptuous visual art than to the sacred text: there are numerous spelling mistakes, and a whole page is repeated. This suggests that the book was never intended for practical use in readings at Mass but was, rather, understood from the start precisely as an extraordinary object.

The book’s richness lies in what Roger Stalley, the art historian, has called “the constant humour and vitality of the ornament, the freshness of the pigments, the unwavering beauty of the script and the haunting ambiguity of the religious imagery”.

Its genius is that it is sacred but never solemn. The vividness, vibrancy and constant, joyful invention make it seem almost a living thing.

Where to see it Old Library, Trinity College Dublin, 01-8962320, tcd.ie/ library/bookofkells