Let us imagine a land called Aqua. Aqua is a desert land, but because water is so important to these desert people, their culture centers around its worship. And in Aqua, there are legends of a place, far across the desert, where water is abundant. (Somewhere, over the rainbow...) Over the centuries, various Aquans attempt to cross the barren desert and find this place where water is plentiful. And, at long last, a few hardy pilgrims succeed. They find a place with a great lake, and, for the first time, some Aquans are able to plunge into a large body of water and swim. They directly experience immersion in water, the movements necessary to swim, the feedback one gets from the water as to when one is swimming well or poorly, what it is to flounder in the depths and nearly drown, and so on. And this immersion is a transformative experience for those who undergo it. Those experiences are first reality. Naturally, when these pioneers return to Aqua, they try to communicate their ex...