An old woman, nearly blind from an eye disease, consulted a doctor. They made an agreement in front of witnesses: she would pay a high fee only if cured; if not, he would get nothing.
The doctor began treatment. With each visit, he secretly took an item from her house. By the time he declared her cured, the house was empty.
The old woman, seeing her empty house, refused to pay. After repeated refusals, the doctor sued her before the magistrates.
In court, she presented her defense: "The claimant is correct about our agreement. I promised to pay if cured; he promised nothing if he failed. He says I'm cured, but I say I'm blinder than ever. When my eyes were bad, I could at least see my furniture. Now that he says I'm cured, I can see nothing in my house at all."