The Wealth of Nations by Part 2 Chapter 4 Page 5

stock. If he wants it as a capital for employing industry, it is from those goods only that the industrious can be furnished with the tools, materials, and maintenance necessary for carrying on their work. By means of the loan, the lender, as it were, assigns to the borrower his right to a certain portion of the annual produce of the land and labour of the country to be employed as the borrower pleases.

The quantity of stock, therefore, or, as it is commonly expressed, of money which can be lent at interest in any country, is not regulated by the value of the money, whether paper or coin, which serves as the instrument of the different loans made in that country, but by the value of that part of the annual produce which, as soon as it comes either from the ground, or from the hands of the productive labourers, is destined