That tonne-for-tonne deal—Prof had expounded it Earthside, had been argument for a Terran catapult. But privately he had no enthusiasm for it. Once he had told me, in North America, "Yes, Manuel, I feel sure it would work. But, if built, it will be temporary. There was a time, two centuries ago, when dirty laundry used to be shipped from California to Hawaii—by sailing ship, mind you—and clean laundry returned. Special circumstances. If we ever see water and manure shipped to Luna and grain shipped back, it will be just as temporary. Luna’s future lies in her unique position at the top of a gravity well over a rich planet, and in her cheap power and plentiful real estate. If we Loonies have sense enough in the centuries ahead to remain a free port and to stay out of entangling alliances, we will become the crossroads for two planets, three planets, the entire Solar System. We won’t be farmers forever."