Spirit, citrus and sugar are the trinity that combine to form the classic sour, one of the oldest types of cocktails. One of the most popular members of this group, the Whiskey Sour, has sated thirsty drinkers for more than one and a half centuries. It’s unknown exactly when the cocktail was conceived (or who was the architect), but its history stretches back to at least the administration of Abraham Lincoln, and the first printed recipe appeared circa 1862 in Jerry Thomas's famed book The Bar-Tenders Guide. The Whiskey Sour was traditionally made with whiskey, lemon juice, sugar and egg white, an ingredient that tames the tart flavor and creates a richer, smoother texture. Today the egg is optional, and it’s often more common to find bars serving Whiskey Sours without egg white. But if you want to taste the original incarnation of the drink, and put a little protein in your system, give it a try.