How can you know what is useful to the world? The world will not tell you. The world will merely let you know what it wants, which changes from moment to moment, and is nearly always cockeyed. You cannot allow yourself to be directed by its tastes. When a writer wonders, “Will it sell?” he is lost, not because he is looking to make an extra buck or two, but rather because, by dint of asking the question in the first place, he had oriented himself toward the expectations of others. The world is not a focus group. The world is an appetite waiting to be defined. The greatest love you can show it is to create what it needs, which mean you must know that yourself.
– Roger Rosenblatt, Unless it Moves the Human Heart, p. 151.