’Tis not in mortals to command success,
But we’ll do more, Sempronius; we’ll deserve it.

These lines come from Joseph Addison’s tragedy "Cato" (1713), a Whig-inflected play set in the last days of the Roman republican Cato the Younger at Utica, resisting Julius Caesar. In the scene, Cato responds to Sempronius amid political crisis and uncertainty, stressing that outcomes are not fully within human control. The play quickly became a touchstone in 18th-century Britain and the American colonies for its rhetoric of virtue, liberty, and public duty; this couplet in particular was frequently excerpted as a maxim about moral effort versus fortune.

Addison contrasts external success—subject to chance, fate, or forces beyond one’s power—with the one domain that remains fully accountable: moral desert. The line argues that while people cannot guarantee results, they can guarantee the integrity of their intentions and actions. In the world of "Cato," this is also a political ethic: republican virtue is measured not by victory but by steadfastness and honor under pressure. The couplet’s enduring appeal lies in its stoic practicality: it reframes ambition away from control of outcomes and toward the cultivation of character.

1) "’Tis not in mortals to command success; / But we’ll do more, Sempronius, we’ll deserve it."