A mighty pain to love it is,
And ’tis a pain that pain to miss;
But of all pains, the greatest pain
It is to love, but love in vain.

Cowley’s stanza turns on a paradox: love is inherently painful, yet the absence of love is painful too. By stacking “pain” against “pain” in balanced clauses, the speaker measures different kinds of suffering—loving, missing, and the compounded torment of unreturned affection. The closing line (“to love, but love in vain”) identifies the worst case as emotional expenditure without reciprocity, where desire produces no consolation, only self-consuming longing. The tight, epigrammatic structure and repetitive diction mimic the obsessive circling of a mind caught in disappointed attachment, a common theme in seventeenth-century lyric treatments of love as both pleasure and affliction.