A canticle for Leibowitz - Walter M. Miller Jr

First there was the Fallout, the plagues and the madness. Then the bloodletting of the Simplification began, when the people - those few who were left - turned against the rulers, the teachers and the scientists who had turned the world into a barren desert, where great clouds of wrath had destroyed the forests and the fields. All knowledge was destroyed, all the learned killed - and only Leibowitz managed to save some of his books. And the monks of the Order of Leibowitz kept the sacred relics, copying, illuminating and interpreting the holy fragments, slowly fashioning a new Renaissance in a barbarous and fallen world.