All labour is directed towards producing some effect.

Producer's Surplus is a convenient name for the genus of which the rent of land is the leading species.

Slavery was regarded by Aristotle as an ordinance of nature, and so probably was it by the slaves themselves in olden time.

All labour is directed towards producing some effect.

Knowledge is our most powerful engine of production.

Nature's action is complex: and nothing is gained in the long run by pretending that it is simple, and trying to describe it in a series of elementary propositions.

Material goods consist of useful material things, and of all rights to hold, or use, or derive benefits from material things, or to receive them at a future time.