Frank Sibley's ideas have been particularly influential among contemporary philosophers interested in aesthetics. Most studies, however, have focused only on his earlier works. In this essay, I explore Sibley's account of the adjectives beautiful and ugly, paying particular attention to three papers that have only recently been published and that have not yet received adequate attention. In particular, I discuss his account of the adjective beautiful, which relies on the controversial notion of an aesthetic ideal. In addition, I discuss an account of how aesthetic judgements may change in relation to our coming to know the kind of object being judged and whether, as Sibley maintains, beautiful and ugly are asymmetric in the sense specified by the author.