I'm not sure how many non-historians in the west realise that nearly all that survives of the great literary Roman and Greek civilisations does so because while Europe was falling into chaos and darkness, medieval Irish monks learned to read and write, and then compulsively copied everything they could get their hands on. Not only that, but the copies they made are masterpieces of illumination, art that is still displayed in museums and reproduced on prints and carvings and jewellery:

"The Irish received literacy in their own way, as something to play with. . . . [W]ithin a generation the Irish had mastered Latin and even Greek and, as best they could, were picking up some Hebrew. . . . [T]hey devised Irish grammars, and copied out the whole of their native oral literature. . . . [T]hey found the shapes of letters magical. Why, they asked themselves, did a B look the way it did? Could it look some other way? Was there an essential B-ness? The result of such why-is-the-sky-blue questions was a new kind of book, the Irish codex; and one after another, Ireland began to produce the most spectacular, magical books the world had ever seen." [pp. 164-6]

Cahill tells the story of these works of art, how they came to be, and why they are largely responsible for survival of our intellectual heritage.