According to this .pdf Lenin didn't exactly say it either; that Keynes gleaned it from an interview of Lenin.
So, banyon, you need to visit the grave of Keynes and pin a correction on him. That is after you write to Brainy Quote.
“The power to declare war, including the power of judging the causes of war, is fully and exclusively vested in the legislature.” ~ James Madison, Father of the Constitution
“We do not believe in aggressive or preventive war. Such war is the weapon of dictators, not of free democratic countries like the United States.”~ Truman, Sept 1, 1950