“The accumulation of all powers … in the same hands, whether of one, a few, or many, and whether hereditary, self-appointed, or elective, may justly be pronounced the very definition of tyranny.” —James Madison (1788) in Federalist Paper, No. 47

This quote is from The Federalist Paper, No. 47.  To read the entirety of this, please see:

http://www.constitution.org/fed/federa47.htm