Donald Trump did not invent the art of the political insult but he's inflamed the level of vitriolic public discourse and incivility to a new low unmatched by other presidents. In a tainted tradition that has permeated our history, other presidents have not been immune to dishing out acerbic insults against one another.

John Quincy Adams was livid that Harvard University planned to award President Andrew Jackson with an honorary degree. He wrote in his diary that Jackson was "a barbarian who could not write a sentence of grammar and hardly could spell his own name."

Franklin Pierce was not as impressed with Abraham Lincoln as history has been, declaring the day after Lincoln issued the Emancipation Proclamation that the president had "limited ability and narrow intelligence."

The list of spicy presidential insults goes on and on. While such statements are often laugh-aloud funny, they are also shocking and sobering. How can these men who have reached the pinnacle of political power be so crude and demeaning? We can learn a valuable lesson from the friendship and feud between John Adams and Thomas Jefferson, and their ultimate reconciliation.

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-Thom