Answer:
James Madison is known as the Father of the Constitution, and he worked very hard to limit the powers of the government branches, so that no government branch would be more powerful than the other two. He was a great supporter of the Bill of Rights, which also limited the power of the government towards the citizens of the nation.
This specific quote refers to the checks and balances system that prevents any of the three branches of the US government; executive, legislative and judicial, from becoming too powerful.