 Obligation refers to the “moral necessity” at work in such relationships, by which one is “bound” to do, admit, or suffer something (DJN I.1.21), and thus it applies to all spheres where authority, right, or other forms of moral normativity operate. Pufendorf clarifies obligation at DJN I.6, in his discussion of law, sanction, and the claims of lawgivers. Law differs, he says there (referring to Hobbes, On the Citizen [De cive {1642}] 14.1), from counsel, agreement, and right alike, because by it an obligation is “introduced into a man’s mind by a superior, that is by someone who not only has the strength to threaten some evil against those who resist him, but also legitimate reasons allowing him to demand that our freedom be restricted at his discretion.” (DJN I.6.9; Pufendorf 1994a, p.123) That is, obligation has a dual aspect involving both reason and strength, neither of which can separately give rise to it: the former generates reverence or respect in those who are (or take themselves to be) obligated, and the latter fear. Both are needed, since reverence without fear does not explain the compellingness of obligation, while fear without reverence does not explain its legitimacy (DJN III.4.6). This analysis applies to obligation under both divine and human law, and in the former case, especially, it raises the question of whether voluntarism or intellectualism, or an amalgam, offers a more adequate account of moral duty. The matter has been much debated, starting with Leibniz’s critique (1706; in Leibniz 1972) and Barbeyrac’s defense (1718; in Pufendorf 2003) of Pufendorf (see Schneewind 1996a; Hunter 2004; Lipscomb 2005; Haakonssen 1998; Grunert 2000), and still in recent discussions (see section 5.3 below) of normativity referring back to those earlier treatments (Darwall 2012, Irwin 2011a–b, Pink 2009).