 The phrase “political obligation” is apparently no older than T. H. Green’s Lectures on the Principles of Political Obligation, delivered at Oxford University in 1879–80 (D’Entrèves, p. 3). The two words from which Green formed the phrase are much older, of course, and he apparently thought that combining them required no elaborate explanation or defense. In any case, there was nothing novel about the problem Green addressed in his lectures: “to discover the true ground or justification for obedience to law” (Green 1986, p. 13). Sophocles raised this problem in his play Antigone, first performed around 440 BCE, and Plato’s Crito recounts Socrates’ philosophical response to the problem, in the face of his own death, some forty years later.