"In order to lay a due foundation for that separate and distinct exercise of the different powers of government, which to a certain extent is admitted on all hands to be essential to the preservation of liberty, it is evident that each department should have a will of its own..."
Source: James Madison, President of the United States (1809-1817), The Federalist Papers: No. 51, published February 8, 1788
In this excerpt, Madison emphasizes the importance of which of the following?