It is clear that Sagan is working within the context of the Cold War, the time during which the United States and the former Soviet Union, along with their respective allies, were engaged in a prolonged dispute over geopolitical territories and particular political philosophies. The Cold War lasted from the post-World War II period to the late 1980s, and it still continues to hover over geopolitical realities to this day. The author is clearly concerned with the fate of the Earth—he also addresses such hot-button issues as climate change, colonialism, and social justice—but he focuses specifically on the preponderance of nuclear armaments and on the countries most likely to wield them: “The global balance of terror, pioneered by the United States and the Soviet Union, holds hostage the citizens of the Earth” (326). Clearly, the world and its primary concerns have changed in the ensuing 40-plus years; however, these concerns are not yet eradicated. The author repeatedly addresses the idea that “Every thinking person fears nuclear war, and every technological state prepares for it” (320). The inevitability of this kind of preparation keeps the author looking for potential answers, including the idea that humanity will eventually unite as one—perhaps the only one—curious and intelligent species.