The Wealth of Nations
Find it online ↗Overview
Smith's 1776 foundation stone of modern economics - the division of labour, the "invisible hand," and the argument that self-interested exchange, under the right institutions, produces public prosperity. Equal parts economic theory, history, and a polemic against mercantilism.
My notes
I haven't written up my thoughts on this one yet. Check back, or read it yourself in the meantime.