Kennedy emphasizes that the economic base of a nation is crucial for sustaining its military and political power. He illustrates how economic resources enable countries to build and maintain powerful militaries, which in turn protect and expand their economic interests. This idea is central to understanding the rise and fall of great powers throughout history.

The book explores the concept of the balance of power, where no single nation is allowed to dominate. Kennedy discusses how alliances and counter-alliances have been formed to maintain this balance, preventing any one power from becoming too dominant. This theme is critical in understanding the strategic decisions made by nations to preserve their own security and influence.

Kennedy highlights the role of technological advancements and military innovations in shifting the balance of power. He provides examples of how new technologies, from naval advancements to nuclear weapons, have given certain nations a strategic edge. This theme underscores the importance of innovation in maintaining and enhancing a nation's power on the global stage.