Whether served neat, on the rocks, or stirred into a cocktail, whiskey is often praised as the finest spirit in the world. On paper it might sound like a simple concoction--water and grain, fermented by yeast, then aged in a wood cask--but whiskey is about so much more than its physical ingredients. During the middle ages, Europeans called it aqua vitae, or "water of life," a name that speaks to the cultural, social, and historical significance that...