 IR theory, however, has a long tradition of drawing on the work of other social sciences.The use of capitalizations of the "I" and "R" in international relations aims to distinguish the academic discipline of international relations from the phenomena of international relations.Many cite Sun Tzu's "The Art of War" (6th century BC), Thucydides' "History of the Peloponnesian War" (5th century BC), Chanakya's "Arthashastra" (4th century BC), as the inspiration for realist theory, with Hobbes' "Leviathan" and Machiavelli's "The Prince" providing further elaboration.