Robert Lucas said: "In practice, it is much more painful to put a modern economy through a deflation than the monetary theory we have would lead us to expect. I take this to mean that we have ‘price stickiness.' " What does Lucas mean by "the monetary theory we have"? What events may have led Lucas to conclude that it is more painful to reduce the inflation rate than theory would predict? Why does he conclude that the U.S. economy apparently has "price stickiness"?