A Marine Corps lesson in hydration—and evangelism. During sone memorable week of grueling training in the sweltering swamps of Quantico, VA, we lost a few Marines to the hospital from dehydration and heat stroke. The Navy corpsman, who was tending to our health at the time, started checking on us more frequently. During one of his visits on a long hot day in the field, he did something I’d not seen before – he began passing out pinches of salt and then asked us how it tasted.