«Thus is his cheek the map of days outworn,
When beauty lived and died as flowers do now».
Because the young man epitomizes ancient standards of true beauty, he does not need cosmetics or a wig made from “the golden tresses of the dead.”
Thus is his cheek the map of days outworn,
In these sonnets, the poet exhibits a general tendency to censure poetic extravagance and to identify such lavishness with the youth’s false friends, as well as with the cosmetic vogue, which the poet castigates as “bastard signs of fair.” So the poet invokes the natural beauty — “Without all ornament, itself and true” — of classical times.
Sonnet 68 and the previous sonnet are more concerned with the poet’s criticism of his cultural age than criticism of the young man. Perhaps because the poet has been spurned by this cultural age, he retaliates against other artists and poets. Or perhaps because the definition of beauty is changing, the poet fears that the young man will no longer be seen as the standard of beauty; his own sonnets will then be viewed as old, stale, outdated verse. Whatever the reason, the poet strongly condemns this general decline in what is perceived as beautiful. For the poet, the young man remains natural beauty, while the contemporary world is “false Art.”
English audio from YouTube Channel Socratica
Summary from Cliffsnotes.com