Abstract: With regard to the nature of art,Western aesthetics has undergone roughly three stages:the first being from ancient Greek days to Renaissance and neoclassicism (600 B.C-1600),which was the ancient natural noumenon period of Western aesthetics,the “artistic imitation of nature” since ancient Greece being its main theme,the theory of “Art is the mirror of nature” during the Renaissance being its variations;the second being from the Enlightenment to German classic aesthetics (from 18th century to the middle of 19th century),which was the contemporary epitemologic period of Western aesthetics,the “imitation theory” and the “mirror theory” remoulded by epitemologic concepts being its main theme,the “theory of artisctic expression” being its variations;the third being from Marxist practical aesthetics,Russian revolutionary democratic aesthetics and Western modernistic aesthetics to Neo-Marxist aesthetics and post-modernistic aesthetics(from the middle of 19th century to the end of 20th century),in this stage,there being no main theme but variations,various concepts,and strange tunes.The three stages,just like a trilogy unfolding diachronically,were more or less connected with men,men's society,men's spititual factors and men's languages.

Key words: Western aesthetics, artistic nature, natural noumenon aesthetics, epitemologic aesthetics,human noumenon aesthetic