“Unthrifty loveliness, why dost thou spend”
'Unthrifty' means wasteful or improvident — someone who squanders a fortune rather than husbanding it. The poet opens the sonnet by calling the young man's beauty a kind of economic recklessness: he has been given a great endowment but is spending it on himself instead of passing it on.
historical The procreation argument (Sonnets 1-17)“beauteous niggard, why dost thou abuse / The bounteous largess given thee to give? / Profitless usurer”
'Niggard' is a miser — someone who hoards rather than spends. A 'usurer' lends money at interest for profit. The poet calls the Youth a 'profitless usurer': he trades exclusively with himself (enjoys his own beauty) yet produces nothing — the opposite of what usury is supposed to achieve. 'Largess' means a generous gift or bounty.
historical Usury and the bond“when nature calls thee to be gone, / What acceptable audit canst thou leave?”
An 'audit' is a formal examination of financial accounts — the official reckoning of what a steward has done with the funds entrusted to him. At death, the poet asks, what satisfactory account of your life could you present? The word frames mortality as a legal settlement: you will be called to answer for how you spent what Nature gave you.
“Thy unused beauty must be tombed with thee, / Which, used, lives th' executor to be”
The couplet is the sonnet's clinching turn. An 'executor' is the person appointed to carry out the terms of a will after the testator dies — to distribute the estate. The poet argues that a child who inherits the Youth's beauty is beauty's executor, ensuring it outlives its original owner. Beauty hoarded dies with the hoarder; beauty 'used' (reproduced in offspring) lives on to settle the estate.
historical The procreation argument (Sonnets 1-17)historical The sonnet form