Alfred Marshall

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

Civilized countries generally adopt gold or silver or both as money.

The hope that poverty and ignorance may gradually be extinguished, derives indeed much support from the steady progress of the working classes during the nineteenth century.

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.

The price of every thing rises and falls from time to time and place to place; and with every such change the purchasing power of money changes so far as that thing goes.