Neither maximalist presidents nor retrenchment presidents have desived a successful and sustainable formula for managing America's role in the world.Both have regularly yielded to blindness, inertia, and overconfidence. It is easy to think of maximalists as more likely to “overdo” it, but retrenchers have overdone things too --- in the opposite direction. As we will see, neither has had much luck trying to change course.Each has instead had to be rescued from error by the other. This is what makes their stories so important to understand. In worshipping at the shrine of foreign policy continuity, Americans ignore what may be the single most important lesson that our history teaches: that discontinuity has been the source of our greatest success.