Who said'i am persuaded no constitution was ever before so well calculatd as ours for... self-government?

The quote "I am persuaded no constitution was ever before so well calculated as ours for... self-government" is attributed to James Madison. He expressed this sentiment in the context of discussing the strengths of the U.S. Constitution and its ability to promote effective self-governance. Madison, one of the Founding Fathers and the fourth President of the United States, believed that the Constitution was designed to balance power and protect individual liberties.