The poem is built on two conventional subjects for Elizabethan sonneteers. The notion of the exchange of hearts was popularized by Petrarch's Sonnet 48; instances may be found in Philip Sidney ("Countess of Pembroke's Arcadia") and others, but the idea is also proverbial. The conceit of love as an escape for an aged speaker is no less conventional and is more narrowly attributable to Petrarch's Sonnet 143. The image cannot be used to date the sonnet, if you agree with most critics, that it was written by a poet in his mid-30s. Samuel Daniel employs the same concept in a poem written when Shakespeare was 29, and Michael Drayton used it when he was only 31. Stephen Booth perceives an echo of the Anglican marriage service in the phrasing of the couplet.