It is a truism to say that the discipline of international relations (IR) is primarily concerned with relations between states. That is not to say that IR is only concerned with states, but by definition, relations between states is what the discipline is largely about. One of the criticisms often leveled at IR as a discipline, and often by historians, is that it lacks sufficient historical perspective. This is a generalization that is obviously not true of all members of the discipline. Yet the criticism cannot be summarily dismissed. While plenty of IR textbooks will tell you that Thucydides (c. 460–400 BCE) is the founding father of realism, this is more about the study of historians and their relevance to the discipline than the study of history.[1] Thinkers such as Machiavelli (1469–1527) and Immanuel Kant (1724–1804) are often treated similarly by the discipline. Perhaps one of the reasons for this shortcoming is that the international states system only emerged following the Peace of Westphalia of 1648, hence IR has its historical limits.