“sweet ornament which truth doth give”
'Truth' here means inner constancy and genuine worth, not simply honesty. An 'ornament' in Elizabethan usage is something that adds real value rather than mere decoration — the poet's argument is that outer beauty gains its full force only from the inner quality that 'truth' supplies.
“canker blooms have full as deep a dye”
'Canker blooms' are wild dog-roses (Rosa canina), not the cultivated, fragrant rose. They open with the same vivid color — 'as deep a dye' — as the perfumed rose but have no scent. The 'canker' in 'canker-rose' comes from the worm or caterpillar ('canker-worm') that infests roses; the word had already come to suggest disease or corruption.
“play as wantonly When summer's breath their masked buds discloses”
'Wantonly' means freely and without restraint — not necessarily immorally, but carelessly, as something that grows or moves without discipline or purpose. 'Masked buds' are petals still enclosed in their calyx, like a face hidden behind a mask; 'discloses' means opens or reveals. The canker blooms open as freely and visibly as the garden roses but have nothing within worth disclosing.
“Sweet roses do not so; Of their sweet deaths, are sweetest odours made”
The poet's central paradox: the cultivated rose's death is the source of its greatest gift. Rosewater and attar of roses are distilled from the petals after they are stripped from the plant — the rose gives its fragrance most fully in dying. The triple repetition of 'sweet' is deliberate, stressing that the rose's value multiplies through its end rather than being extinguished by it.
historical The procreation argument (Sonnets 1-17)“When that shall vade, by verse distills your truth”
'Vade' means to fade away or pass from sight — a poetic archaism even in Shakespeare's own day, lending a formal, solemn tone to this final line. 'Distills' continues the rose-perfume metaphor: just as a dead rose's essence is extracted and bottled, the poet's verse extracts and preserves the youth's inner 'truth' after his physical beauty has faded.
historical The Fair Youth, the Dark Lady, and the Rival Poet