Nobody has ever measured, not even poets, how much the heart can hold.

The line asserts that human emotional capacity—especially for love, longing, grief, and endurance—defies quantification. By singling out poets, traditionally credited with giving language and measure to feeling, the speaker heightens the claim: even those most skilled at articulating emotion cannot fully “measure” what the heart can contain. The quote thus celebrates the heart’s expansiveness and mystery, suggesting that inner life exceeds the limits of description, art, or rational accounting. It can be read as both consoling (we can hold more than we think) and tragic (the heart can hold immense pain as well as joy).