I think [John Adams] developed a much deeper suspicion of France and the other European powers than he had earlier. He lost much if not all of the utopian thinking about international politics and diplomacy expressed in his Model Treaty of 1776 and became much more cynical about the world.

Americans, [John Adams] wrote in 1780, believed that their "revolution is as much for the benefit of the generality of Mankind in Europe, as for their own."

The relationship between [John] Adams and [Tomas] Jefferson was extraordinary. They differed on every conceivable issue, except on the Revolution and the love of their country.

By the time [John Adams] came to write his Defence of the Constitutions of the United States in 1787 he had as dark a view of the American character as that of any critic in our history.

[John] Adams identified himself with the political theories of [James] Harrington, [John] Locke, and [Charles-Louis] Montesquieu, whose ideas of constitutionalism, he believed, were applicable to all peoples everywhere; they were his contribution to what he called "the divine science of politics."

If history teaches anything, it teaches humility.

[John] Adams never had an optimistic view of human nature, and his experience in the Congress and abroad only deepened his suspicion that his fellow Americans might not have the character to sustain a republican government.