Many people don't realize that this country's original constitution - The Articles of Confederation - contained term limits for members of Congress.
In Article V of that document, it stated:
No State shall be represented in Congress by less than two, nor more than seven members; and no person shall be capable of being a delegate for more than three years in any term of six years; nor shall any person, being a delegate, be capable of holding any office under the United States, for which he, or another for his benefit, receives any salary, fees or emolument of any kind.
(Emphasis mine)
John Adams, in the Continental Congress, argued in favor of the term limits. As recorded by George Will in Restoration: Congress, Term Limits, and the Recovery of Deliberative Democracy:
In the era of America's founding, the most frequent argument for term limits were that limits would be prophylactic measures against tyranny. Thus the Massachusetts delegation to the Constitutional Convention [of 1787] was specifically instructed "not to depart from the rotation established in the Articles of Confederation. Delegate John Adams believed rotation would "teach" representatives "the great political virtues of humility, patience. and moderation without which every man in power becomes a ravenous beast of prey." Adam's colleague, Elbridge Gerry said, "Rotation keeps the mind of man in equilibria (sic) and teaches him the feelings of the governed" and counters the "overbearing insolence of office." Adams and Gerry were echoing the thinking that produced Article VIII of the Declaration of Rights in the Massachusetts Constitution of 1780, which declared that citizens have a right to expect "public officers to return to private life" "in order to prevent those, who are vested with authority, from becoming oppressors."
Indeed, one Congress of the Confederation sent home a delegate who had showed up for a fourth one-year term, inside of the six-year framework. Noted in the rolls, the delegate was sent home for "tarrying too long."