“My bounty is as boundless as the sea, / My love as deep; the more I give to thee, / The more I have, for both are infinite.”

This is Shakespeare's only sonnet with a double ending, and the couplet in the middle is the one that keeps ending up on cards. The logic is deliberately circular: what the speaker gives away is the very thing that makes him richer, which is a Valentine's sentiment dressed as a piece of arithmetic.