The Social Contract by Jean-Jacques Rousseau

As, before putting up a large building, the architect surveys and sounds the site to see if it will bear the weight, the wise legislator does not begin by laying down laws good in themselves, but by investigating the fitness of the people, for which they are destined, to receive them. Plato refused to legislate for the Arcadians and the Cyrenaeans, because he knew that both peoples were rich and could not put up with equality; and good laws and bad men were found together in Crete, because Minos had inflicted discipline on a people already burdened with vice.

A thousand nations have achieved earthly greatness, that could never have endured good laws; even such as could have endured them could have done so only for a very brief period of their long history. Most peoples, like most men, are docile only in youth; as they grow old they become incorrigible. When once customs have become established and prejudices inveterate, it is dangerous and useless to attempt their reformation; the people, like the foolish and cowardly patients who rave at sight of the doctor, can no longer bear that anyone should lay hands on its faults to remedy them.