Hume

From: Monetary Theory before Adam Smith by Arthur Eli Monroe, Ph.D. Assistant Professor of Economics, Harvard University. Glouster, Mass. Peter Smith, 1965.

Hume had little interest in the logical basis of the quantity theory, but was principally concerned with its qualifications. 'It seems a maxim almost self-evident,' he writes, 'that the prices of every thing depend on the proportion between commodities and money.' The only hint as to his reasons for this opinion is his remark, in another connection, that the precious metals 'are considered chiefly as representations.' It is not the absolute quantity of money and commodities, however, which is meant in the above statement, he carefully points out, but the commodities 'which come or may come to market,' and the money which circulates. Coin locked up and goods not sold obviously have no effect on prices. Hence it is that prices are lower in France than in some countries not having half as much gold and silver: people are in the habit of keeping large sums in their coffers, because the use of credit instruments is undeveloped, and much of the metal is in use as plate.

...the commodities 'which come or may come to market,' and the money which circulates.