Dear Dr. Boli: I know what butter is, but what is “margarine”? How is it made? And why isn’t it pronounced the way it’s spelled? —Sincerely, Mario Batali.

Dear Sir: Margarine is the by-product of the butter-making process. When butter is made, it must pass rigorous inspections to be legally sold as “butter.” The flavor, texture, and color are carefully regulated and controlled. Thus only a little less than half an average dairy’s output of churned cream can legally be sold as “butter.” The rest must be sold as “margarine” to denote its inferior quality. The dairy industry has petitioned the FDA to allow margarine to be sold as “butter factory seconds,” but so far without success.

As for the pronunciation with a soft G, that is a corruption introduced through ignorance and illiteracy. A G followed by an A is always hard, and “margarine” was so pronounced by all educated persons until after the Second World War. Dr. Boli still pronounces it the correct way, and he recommends that you do the same. A mistake is still a mistake, no matter how often repeated.