Full Idea
When we consider how nearly equal all men are in their bodily force, and even in their mental powers and faculties, till cultivated by education, ...then nothing but their own consent could at first associate them together, and subject them to authority.
Gist of Idea
People must have agreed to authority, because they are naturally equal, prior to education
Source
David Hume (Of the original contract [1741], p.276)
Book Reference
Hume,David: 'Selected Essays' [OUP 1996], p.276
A Reaction
This doesn't sound very convincing. Some people are much better suited than others to training and education. Men vary enormously in size.