How we cite our quotes: (Book.Chapter.Paragraph)
Quote #10
We should not call a marriage barren or unproductive, though it produced only a son and a daughter, to replace the father and mother. (4.9.18)
Smith says that one of the most important things for economies is constant growth, which means that two parents have to have at least two kids to replace them. Otherwise, the population might start going down and there won't be enough young people to take care of the old.