Henry Hazlitt opens with his central methodological principle: sound economic analysis requires considering both the immediate, visible effects of a policy and its longer-term, less visible effects on all groups affected, not just the intended beneficiaries.

Why this dual consideration matters:

• Many economic policies produce an immediately visible benefit for a specific group while producing less visible costs distributed elsewhere in the economy
• Analysis focused only on the immediate, visible effect on the intended beneficiary group systematically misses these broader, less visible costs
• Hazlitt's central methodological lesson, applicable across many specific economic policy questions, is to actively trace out these less visible secondary effects

This opening establishes the book's core analytical method, applied throughout its subsequent examination of specific economic policy fallacies.