[NCangler]

"If men were angels, no government would be necessary. If angels
were to govern men, neither external nor internal controls on
government would be necessary. In framing a government which is
to be administered by men over men, the great difficulty lies in
this: you must first enable the government to control the governed;
and in the next place, oblige it to control itself."

-- James Madison (Federalist No. 51, 8 February 1788)

Reference: Madison, Federalist No. 51.