Prices of goods depend upon the expenses, the interest of money employed, and the “labours too, the care, attention, accounts and correspondence about them.” Sometimes we must “take in also the condition of the person so employed,” since “the expense of his station of life must be defrayed by the price of such labours; and they deserve compensation as much as any other. This additional price of their labours is the just foundation of the ordinary profit of merchants.”
In the next chapter, on “The Principal Contracts in a Social Life,” we find the rent or hire of unfruitful goods, such as houses, justified on the ground that the proprietor might have employed his money or labour on goods naturally fruitful.
“If in any way of trade men can make far greater gains by help of a large stock of money than they could have made without it, ’tis but just that he who supplies them with the money, the necessary means of this gain, should have for the use of it some share of the profit, equal at least to the profit he could have made by purchasing things naturally fruitful or yielding a rent. This shows the just foundation of interest upon money lent, though it be not naturally fruitful. Houses yield no fruits or increase, nor will some arable grounds yield any without great labour. Labour employed in managing money in trade or manufactures will make it as fruitful as anything. Were interest prohibited, none would lend except in charity; and many industrious hands who are not objects of charity would be excluded from large gains in a way very advantageous to the public.”