wrote Jean le Rond d'Alembert, "Let us not seek the chimera of perfection, but that which is the best possible." In England, in 1757, the important aesthetician Edmund Burke denied that perfection was the cause of beauty. Quite the contrary, he argued that beauty nearly always involved an element of imperfection; for example, women, in order to heighten their attractiveness, emphasized their weakness and frailty, which is to say, their imperfection. The 18th century was the last for which perfection was a principal concept in aesthetics. In the 19th century, perfection survived only vestigially as a general expression of approval. Alfred de Musset held that "Perfection is no more attainable for us than is infinity. One ought not to seek it anywhere: not in love, nor beauty, nor happiness, nor virtue; but one should love it, in order to be virtuous, beautiful and happy, insofar as that is possible for man." In the 20th century, Paul Valéry wrote: "To strive for perfection, to devote endless time to a work, to set oneself—like Goethe—an unattainable goal, are all intents that are precluded by the pattern of modern life." The dismissal of the question concerning whether artists can achieve perfection, still left the question: Do artists want to achieve it? Is that their actual goal? Some artists, schools and epochs have aimed for perfection. Others have nurtured other goals: pluralism, novelty, powerful sensations, faithfulness to truth, self-expression and expression of the world, creativity and originality — all of which may roughly be summarized as "expression." There have been ages of perfection, and ages of expression. The arts of ancient Greece, the Renaissance and neoclassicism were arts of perfection. In the mannerist, baroque and romantic periods, expression has prevailed. Ontology and theology The Greek philosopher Anaximander described the world as "endless" (apeiron), Xenophanes — as "the greatest" (megistos). But while they ascribed great qualities to the world, they did not regard it as perfect. Only Parmenides seems to have considered existence to be "tetelesmenon" ("finished"); and Melissos, his successor in the Eleatic school, said that existence "was entirely" ("pan esti"). Thus both saw perfection in existence; true existence was one, constant, immutable. Moreover, Parmenides thought the world to be finite, limited in all directions, and like a sphere — which was a mark of its perfection. Parmenides' view was embraced to some extent by Plato. He thought that the world was the work