The paradox of decelaration

One day Till Eulenspiegel was leisurely strolling to town.
All over sudden he heard the noise of a nearing vehicle on a road behind him. Soon after a coach came to a halt next to him on a road with pot-holes here and there. The coachman, in a hurry, asked Till, “Tell me urgently – how long will it take me to get to town?”

Till replied, “If you go slowly, it will take half an hour. If you go fast, it will take two hours, sir.”
“You fool”, scolded the coachman churning the horses to a fast gallop. Not long after that the coach was out of sight.

About an hour later Till turned around a corner where he saw a coach lying in the ditch. Its leading axle was broken. Sure enough it was the hurried coachman from before bitching while trying to repair his coach. Addressed with a scornful glance the easygoing passenger repeated to the driver, “As I’ve said: If you go slowly, it will take half an hour.”