As a friend, old boy, I advise you to send for circular (no obligation) and valuable free Art Picture to:— SHORTCUT EDUCATIONAL PUB. CO. Desk WA Sandpit, Iowa.
True, it was a good advertisement at Boosters’ Club lunches, and all the varieties of Annual Banquets to which Good Fellows were invited, to speak sonorously of Unselfish Public Service, the Broker’s Obligation to Keep Inviolate the Trust of His Clients, and a thing called Ethics, whose nature was confusing but if you had it you were a High-class Realtor and if you hadn’t you were a shyster, a piker, and a fly-by-night.
There are no more uses of "obligation" in the book.