Most people find great comfort and repose with water. Perhaps because we begin our lives surrounded in liquid in the womb, this basic familiarity stays with us throughout our lives.

Human beings are comprised primarily of water, and many special characteristics we have link us to aquatic mammals, perhaps carrying the memory of a time when the human species had an “aquatic interlude.” A three-day old fetus is 97 percent water, and at eight months the fetus is 81 percent water. By the time a human has grown to adulthood, the adult body is still 50 to 70 percent water, depending on the amount of fatty tissue.