“Look in thy glass and tell the face”
'Glass' is an Elizabethan word for mirror (flat glass backed with tin and mercury). The speaker tells the youth to look at his own reflection and reckon with what he sees: a face worth reproducing in a child.
“unear'd womb Disdains the tillage of thy husbandry”
'Unear'd' means unploughed (from Old English 'erian,' to plough). 'Tillage' is the cultivation of land by ploughing and planting. 'Husbandry' means farming — but also the duties of a husband. The three words work together as an extended agricultural metaphor: a woman's womb is fertile ground that the youth, as a responsible farmer-husband, should be cultivating.
historical The procreation argument (Sonnets 1-17)“who is he so fond will be the tomb, Of his self-love”
'Fond' here means foolish or doting, not merely affectionate (its primary modern sense). The speaker asks: who is so foolish as to let self-love become his own tomb — that is, to let vanity end with him rather than pass beauty on to a child?
“Die single and thine image dies with thee”
The couplet delivers the poem's logical conclusion with deliberate bluntness: if the youth dies without a child, his face — described throughout as a glass, a mirror, a reflection of his mother — simply goes dark. 'Single' means unmarried and alone. The whole argument collapses to one bare, twelve-word sentence.
historical The procreation argument (Sonnets 1-17)