Herrin’s book, though dense with mention of Theodores, Theodosiuses, Theodoras and Theoderics, is eminently worth reading. The colour plates are so sumptuous that the Ravenna mosaics fairly glow on the page. History teaches us that it is on the margins that the greatest change often occurs. Ravenna was on such a margin. Now, perhaps for the first time, the city emerges triumphant from the shadow of the so-called Dark Ages.