[John Adams and Tomas Jefferson] shared experience in 1775 - 1776 in bringing about the separation from Britain and their service in Europe cemented a friendship that in the end withstood the most serious political and religious differences that one could imagine, especially their differences over the French Revolution. It was probably Jefferson's obsession with politeness and civility that kept the relationship from becoming irreparably broken.

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.

If history teaches anything, it teaches humility.

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.

[John Adams] always felt that his contribution to bringing about independence went unappreciated, especially after the 1790s when [Tomas] Jefferson began to be lauded as the "author" of the Declaration of Independence.

[John] Adams never hid his jealousy and resentment of the other Founders, especially Benjamin Franklin.

[John] Adams's letters to [his wife] Abigail are wonderful. In his letters, he is loving, humorous, preachy, learned, and saucy. He speaks to her with almost complete abandon, revealing all of his sensuous and vulnerable nature.