Lake of constance

On a winter evening amidst andriving snowstorm a man on horseback arrived at an inn,happy to have reached a shelter after hours of riding over the wind-swept plain on which the blanket of snow had covered all paths and landmarks.The landlord who came to the door viewd the stranger with supprise and asked hm whence be came.
The man pointed in the direction straight away from the inn,whereupon the landlord,in a tone of awe and wonder,said:"Do you know that you have ridden across the Lake of Constance?"
At which the rider dropped stone dead at his feet.