Danh ngôn của Alfred Marshall (Sứ mệnh: 4)

Capital is that part of wealth which is devoted to obtaining further wealth.
Civilized countries generally adopt gold or silver or both as money.
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.
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.
But if inventions have increased man's power over nature very much, then the real value of money is better measured for some purposes in labour than in commodities.