In the conclusion to his "A Modest Proposal" Swift explains to the reader that he has no personal gain from his proposal. He explains that he suggests it only because he wants to support his country and help the poor families living there. He points out that in his own family his wife is past the age where she can have any more children, and his youngest (who is nine years old) is too old to be considered for Swift's proposal. From this, the audience is to believe he isn't proposing the plan to make money for himself, but for his county.
I profess, in the sincerity of my heart, that I have not the least personal interest in endeavouring to promote this necessary work, having no other motive than the publick good of my country, by advancing our trade, providing for infants, relieving the poor, and giving some pleasure to the rich. I have no children, by which I can propose to get a single penny; the youngest being nine years old, and my wife past child-bearing.