If someone tells you he or she can define "consideration," don't believe them.

From Lukegilman.co: a Blawgraphy:

In 1965, a law student wrote Yale law professor Arthur Corbin to ask: "Do you know what consideration is?" His response:

If you do, you know more than I and some others know. And yet, in Vols I and IA I have written many chapters about it.

"Vols I and IA" of course, are 2 volumes of Corbin on Contracts, which has been described as "the greatest law book ever written."