Butler's Senate career is noted for an event at which he was not present. Senator Charles Sumner of Massachusetts, during his "Crime Against Kansas" speech in May 1856, denigrated South Carolina and abused Butler personally in terms considered to exceed parliamentary propriety. Sumner likened Butler to Don Quixote and said Butler: "has chosen a mistress to whom he has made his vows, and who, though ugly to others, is always lovely to him; though polluted in the sight of the world, is chaste in his sight. I mean the harlot, Slavery." Senator Stephen Douglas, who was also a subject of criticism during the speech, suggested to a colleague while Sumner was orating that "this damn fool is going to get himself shot by some other damn fool."