Ronald Coase

The law of property determines who owns something, but the market determines how it will be used.

Roughly speaking, when you are dealing with business firms operating in a competitive system, you can assume that they're going to act rationally. Why? Because someone in a firm who buys things at $10 and sells them for $8.00 isn't going to last very long in that firm.

During the two centuries since the publication of 'The Wealth of Nations,' the main activity of economists, it seems to me, has been to fill the gaps in Adam Smith's system, to correct his errors and to make his analysis vastly more exact.

We must first note that economic factors are taken into account in a world in which ignorance, prejudice, and mental confusion, encouraged rather than dispelled by the political organization, exert a strong influence on policy making.