"inertia is like the currents of the Mississippi River. It's a force that ebbs and flows, and if you aren't careful, it can drive your craft in directions you hadn't intended to follow. Captains on the Mississippi, as on any large body of water, must learn the currents, know the capabilities of their vessels, and understand how to steer. They can't change the currents, but they can learn to work with them to minimize the interference and even to use it. "