In the Philebus beauty is combined with truth and proportion in order to constitute a triad which, the absolute good not being directly accessible, can help to assess the goodness of a mixture. The present article examines the mutual relation between the terms of the triad as well as between the triad and the good. The interpretation hinges on the distinction between the "order of the good" and the "order of nature" which is to be found in the Republic (493 c): art, which only has the intention to realize an appearance of beauty, is said to belong to the natural order (the object of which are the necessities and needs of nature, and also that which the artist conceives as the need of his audience). This conception of alleged beauty is contrasted with true beauty, which contains in itself truth and proportion, thus being an expression of the good.
Van Riel, G. (1999). Beauté, proportion et vérité comme ‘vestibule’ du bien dans le ‘Philèbe’. Revue Philosophique de Louvain, 97(2), 253-267. https://doi.org/10.2143/RPL.97.2.541949 (Original work published 1999)