Final answer:
The source of the phrase "ambition must be made to counteract ambition" is George Washington's farewell address, emphasizing the need for checks and balances in government.
Step-by-step explanation:
The source of the phrase "ambition must be made to counteract ambition" is George Washington's farewell address. In his address, Washington emphasized the need for a system of checks and balances to prevent the concentration of power in any one branch of government. This concept of ambition being checked by ambition is crucial to maintaining a healthy democracy.
Learn more about George Washington's farewell address