Above all, a spy needs to avoid blunders. The title of this painting doesn’t refer to keeping secrets, but rather to saying only what you must. We all say dumb things, but embarrassment is usually all we suffer. For a spy, the penalty can be far greater. Imagine you’re recruiting a new spy and one day you make a negative comment about a particular book. He quickly informs you—with an icy glare—that the book was written by a close friend of his. He may never forget your comment. So if you hope to become a spy, write this down: never make strong statements when you don’t have to.