Realist international relations scholars have approached the connection between economics and security in two ways. Cold War-era realists derived the national interest from the international balance of power, and assessed the utility of both military and economic instruments of statecraft. A second realist approach, advanced by E. H. Carr in his 1939 The Twenty Years' Crisis, places interstate competition in the context of another struggle over wealth and power in which no-one's primary concern is the national interest. That is the realm of capitalism (and resistance to capitalism). That deeper set of connections between economics and security was overlooked in Cold War IR literature, at considerable cost to our understanding of world politics. Understanding why Carr's ‘historical realism’ was bypassed can help pave the way for a more fruitful realist approach to comprehending a new era in world politics.