The classical economists referred to the fee paid for the use of money or stock as "interest" but declared this to be a derivative income.
The distinction between interest and profit is murky: "Whoever derives his revenue from a fund which is his own, must draw it either from his labor, from his stock, or from his land.
In Classical Economics profit is the return to the proprietor(s) of capital stocks (machinery, tools, structures).
The great fortunes so suddenly and so easily acquired in Bengal and the other British settlements in the East Indies, may satisfy us that, as the wages of labor are very low, so the profits of stock are very high in those ruined countries.
In Bengal, money is frequently lent to the farmers at forty, fifty, and sixty per cent and the succeeding crop is mortgaged for the payment.
Before the fall of the Roman republic, an usury of the same kind seems to have been common in the provinces, under the ruinous administration of their proconsuls.
The virtuous Brutus lent money in Cyprus at eight-and-forty per cent as we learn from the letters of Cicero.