Let Sporus tremble—“What? that thing of silk,
Sporus, that mere white curd of ass’s milk?
Satire or sense, alas! can Sporus feel?
Who breaks a butterfly upon a wheel?”

These lines come from Alexander Pope’s verse epistle “An Epistle to Dr. Arbuthnot” (1735), a self-defensive satire written late in his career amid intense literary feuds. Pope addresses the physician and satirist John Arbuthnot while justifying his own satirical practice and answering attacks on his character and writing. In the poem he sketches portraits of contemporary figures; “Sporus” is a thinly veiled, venomous caricature of Lord Hervey, a courtier associated with Queen Caroline and a prominent target in Pope’s quarrels with the “Dunciad” circle. The passage dramatizes Pope’s contempt for Hervey’s perceived effeminacy and malice, and it also raises the question of whether such a target is even worth the force of satire.

Pope’s speaker both assaults and belittles “Sporus.” The imagery (“thing of silk,” “white curd of ass’s milk”) is designed to feminize and dehumanize the target, portraying him as soft, insubstantial, and incapable of moral feeling. The culminating question—“Who breaks a butterfly upon a wheel?”—adds a paradoxical restraint: it suggests that to punish such a trivial creature with the heavy machinery of satire would be disproportionate. The line has endured because it captures a general ethical dilemma about overreaction and the misuse of power, even as its original context is a personal and politically charged attack within Pope’s culture of pamphlet wars and courtly intrigue.

“Who breaks a butterfly upon a wheel?” (often quoted alone, detached from the Sporus passage)
“Who breaks a butterfly on a wheel?” (common modernization of the preposition)
“Who breaks a butterfly upon the wheel?” (attested variant in later quotation culture)