the wolf and the lamb

One day the wolf was slaking his thirst at a stream when he chanced to see a lamb, also drinking, at some distance down the stream.
Outraged, he growled, You are muddying my drinking water, now I shall eat you.
The lamb protested, But, Sir, how can I be muddying your drinking water? I am farther down stream than you are. The water is flowing from your part of the stream to where I am.
Upstream or downstream, your drinking is muddying my water, and I shall eat you. So saying, the wolf leaped upon the lamb and devoured him.