" What's your definition of sanity, Skipper?’ ‘The ability to swim,’ said Sparrow. Ramsey felt a cold shock, as though he had been immersed suddenly in freezing water. He had to force himself to continue breathing normally. As though from a great distance, he heard Sparrow's voice: ‘That means the sane person has to understand currents, has to know what's required in different waters.’ Ramsey "

― Frank Herbert , Under Pressure