" To improve their sense of balance,” Mr. Foster explained. “Doing repairs on the outside of a rocket in mid-air is a ticklish job. We slacken off the circulation when they’re right way up, so that they’re half starved, and double the flow of surrogate when they’re upside down. They learn to associate topsy-turvydom with well-being; in fact, they’re only truly happy when they’re standing on their heads. "

― Aldous Huxley , Brave New World