The speaker meditates on how all living things reach perfection for only a fleeting moment. He sees the world as a vast stage where the stars secretly influence human lives, and people flourish and wither like plants under the same sky. This thought of universal decay makes the beloved’s youthful beauty stand out all the more vividly — but it also means that Time and Decay are already working to turn that bright youth into darkness. The mood moves from a calm, almost melancholy observation to a personal, protective devotion. In the closing couplet, the speaker declares his own way of fighting back: as Time steals the beloved’s vitality, he will renew it by grafting the beloved into his poetry, preserving that beauty forever. It’s a quiet but fierce act of love.
Sonnet 15: When I consider every thing that grows — Summary
When I consider every thing that grows Holds in perfection but a little moment, That this huge stage presenteth nought but shows Whereon the stars in secret influence comment; When I perceive that men as plants increase, Cheered and checked even by the self-same sky, Vaunt in their youthful sap, at height decrease, And wear their brave state out of memory; Then the conceit of this inconstant stay Sets you most rich in youth before my sight, Where wasteful Time debateth with decay To change your day of youth to sullied night, And all in war with Time for love of you, As he takes from you, I engraft you new.