Much of our communication is transactional: we want questions to get a job done but not to do more than that. We don't always want to be influenced or even to have much influence; often we just want what we want. If what we want is influence - either to sell or to manage or to teach - then we have to move to a new kind of question.
Great questions are not about information; they are about creating a channel through which information will flow. When someone asks a great question, we begin to connect in new ways, sometimes with the person who asked and sometimes with ideas or experiences that we had not connected before. That new thinking - that learning - can create it's own momenturm.
Think about that. There is somewhere in your experience someone who asked you a question that made you think - and that made a difference. It continues to make a difference, even if you no longer see that person who asked. I remember the interviewer on a scholarship panel who asked me "If you can do math, why do you want to study English?" I remember because I am still answering that question thirty years later.
That's a great question.