The Wealth of Nations by Part 4 Chapter 9 Page 39

continues, at least, the existence of the stock or capital which maintains and employs it. But upon this account alone the denomination of barren or unproductive should seem to be very improperly applied to it. We should not call a marriage barren or unproductive though it produced only a son and a daughter, to replace the father and mother, and though it did not increase the number of the human species, but only continued it as it was before.

Farmers and country labourers, indeed, over and above the stock which maintains and employs them, reproduce annually a net produce, a free rent to the landlord. As a marriage which affords three children is certainly more productive than one which affords only two; so the labour of farmers and country labourers is certainly more productive than that of merchants, artificers, and