AMONG the delights of this superbly civilised biography are the sketches that decorate its pages. As he worked, more often on a rumpled bed than at a desk, Pushkin doodled profiles of his friends, enemies and lovers: caricatures of venal old men with popping eyes and side-whiskers, society beauties with long necks and empire curls and, most touchingly, images of his "cross-eyed madonna" Natalya, catching in quick lines that hint of a squint which bewitched the poet, and one too many men besides.