In "The March of Folly: From Troy to Vietnam," author Barbara W. Tuchman explores various historical instances where societies ignored rational choices and persisted in folly despite clear evidence against their decisions. Through these examples, Tuchman highlights the recurring nature of such behavior throughout history. The book examines how leaders and nations can become blind to the consequences of their actions, leading to disastrous outcomes.

The quote "Each day he grew older and learned something new" encapsulates the essence of personal growth that can be seen in the historical narratives presented in the book. It suggests that wisdom can emerge from experience, yet Tuchman points out that many individuals and governments seem to neglect the lessons that history teaches, continuing to repeat the same mistakes across generations. Through her analysis, she invites readers to reflect on the importance of recognizing and learning from past errors to avoid falling into folly again.