Henry Hazlitt on economics

The whole of economics can be reduced to a single lesson, and that lesson can be reduced to a single sentence.  The art of economics consists in looking not merely at the immediate but at the longer effects of any act or policy; it consists in tracing the consequences of that policy not merely for one group but for all groups.

~ Henry Hazlitt, Economics in One Lesson, Chapter 1: "The Lesson," p. 17