In a tiny village long ago, there was a farmer who produced butter of excellent quality.
As news of the sweetness of the butter became known, the local baker approached the farmer and they came to an amicable agreement whereby each day the farmer sold the baker a pound of his excellent butter.
One day the baker became suspicious and decided to weigh the butter to see if it was a full pound.
When he realized it was indeed not a full pound, the baker in a fit of rage at the injustice, went to the judge to demand restitution.
The judge brought the farmer in for a formal hearing and asked, “Do you weigh the butter you sell to the baker?”.
The farmer replied, “Yes, your honor, but I am a poor farmer and my equipment is humble.”
The judge asked, “What equipment do you use?”
The farmer stated, “I use an equal balance scale. In our agreement the baker brings me a pound loaf of bread in exchange for a pound of butter. Every day I place the loaf of bread he gives me on the scale and give him an equal weight in butter.”