Much has been written about Locke's Second Treatise, but still, I believe, the book's main line of argument has been left unclear. Some concepts need more prominence — the duty to preserve mankind, the right of war, and private judgment; others need less — consent, majority rule, and property. Locke's aim was not to show that political obligation rests upon consent: that is assumed without argument. What he set out to prove is that there are certain limits to political obligation which not even consent could set aside.