What makes a bourbon great?

"Aging makes the bourbon. As it goes in and out the wood, the liquid picks up 75 percent of the flavor. 'White dog' is what we call the unaged bourbon before it goes into the wood; it’s pretty sharp. Has some serious bite. But when you put it away in the rack house, where the bourbon will move in and out of the wood, it softens up, becomes sweeter. It picks up those nice aromas. During the aging process, you lose about 4 percent of the liquid a year, due to evaporation. We call that the 'angel’s share.'

"Take a bourbon like Knob Creek—it’s been aged nine years, so it’s lost roughly a third of the barrel to the angels. But what’s left behind is more concentrated; you're left with the woody flavors, the sweetness, all the things you enjoy in a good bourbon. Without the aging, you’d just have a sharp, clear, corn-based spirit."