In the second quatrain, Shakespeare compares men to plants – both ‘things that grow’. Men, too, grow stronger thanks to the sky, or good weather , just as the same sky influences the growth of plants. But when they have fully grown, they will begin to ‘decrease’, until the world cannot remember how they were in their prime. So, both, stars in the first stanza and sky in this one influence the destinies of human beings.

The fact that Shakespeare rhymes ‘increase’ with its antonym ‘decrease’ points up the cycle of growth and decay, just as ‘sight’ and ‘night’ are put in pointed opposition.

The third stanza represents the turning point, where the poet switches from general and universal considerations to more personal ones.  In lines 11-12 there is the personification of Time and decay, as they debate with each other the best way to destroy youth and beauty.  You understand it because time and decay are written with a capitol letter. Shakespeare concludes by saying that the whole world, for love of the Youth, are at war with Time, so this is, a losing battle. An important aspect is the power of the poet’s verse to memorialize forever the young man’s beauty. In the third quatrain the language reflects the feeling of the speaker - wasteful/decay/sullied/war - who is inflexible that, despite this battle and time's effects, the poetry will renew his beauty.