Jefferson wrote in his Notes on Virginia Q.XIII, 1782 (ME 2:164):
“All the powers of government, legislative, executive, and judiciary … in the same hands is precisely the definition of despotic government …
Let those who doubt it turn their eyes on the republic of Venice …
Legislative, executive and judiciary department should be separate … so that no person should exercise the powers of more than one of them at the same time …
Nor should our assembly be deluded by the integrity of their own purposes, and conclude that these unlimited powers will never be abused, because themselves are not disposed to abuse them.
They should look forward to a time, and that not a distant one, when corruption in this, as in the country from which we derive our origin, will have seized the heads of government, and be spread by them through the body of the people; when they will purchase the voices of the people, and make them pay the price.
Human nature is the same on every side of the Atlantic, and will be alike influenced by the same causes.”