time"s fickle glass

O thou, my lovely boy, who in thy powerDost hold Time's fickle glass, his sickle, hour;Who hast by waning grown, and therein show'stThy lovers withering as thy sweet self grow'st;If Nature, sovereign mistress over wrack,As thou goest onwards, still will pluck thee back,She keeps thee to this purpose, that her skillMay time disgrace and wretched minutes kill.Yet fear her, O thou minion of her pleasure!She may detain, but not still keep, her treasure:Her audit, though delay'd, answer'd must be,And her quietus is to render thee.