Barnum’s foundational principle is that Wealth begins with a single arithmetic rule: income must consistently exceed expenditure. But the real threat to this margin is not obvious extravagance; it is the subtle expansion of lifestyle driven by social comparison, unregulated prosperity, and cascading purchases that each seem small in isolation. True economy is not cheese-paring meanness but a systematic principle, and tracking expenditure is the diagnostic tool that reveals where the margin actually leaks. Without this discipline, even high income cannot produce lasting wealth.