The poetry is in the choices distillers make that affect flavor. All whiskey starts the same way, with a mash of grain, yeast, and water. For rye, the mash is at least 51 percent rye, a spicy grain; for bourbon, it's the same percentage of corn, while corn whiskey contains 80 percent or more of that sweet grain. There are also wheat whiskeys, which tend to be soft and round, and smokey ones made from malted barley. The remaining grains in any mash bill, or recipe—rye, corn, barley, wheat, oats—add their own personalities, and craft distillers have been experimenting with recipes.