Protagoras the Sophist agreed to teach Eualthus the art of pleading, on the condition that Eualthus pay him one half of the fee upon completion of his course and the other half after he [Eualthus] had won his first case in court. Because of Eualthus's failure, upon completion of the course, to practice law, Protagoras decided to collect the other half of the fee. To do this he initiated a court action against Eualthus. As the case came to court Eualthus decided to conduct his own defense. The substance of Protagoras' appeal was as follows:
"If I win this case, Eualthus must pay by order of the court; if I lose, he must pay me by the terms of our contract. I shall either win the case or lose it. In either event Eualthus must pay the fee."
The following was Eualthus' rebuttal:
"If I win this case, I shall not have to pay by reason of the court's decision. If I lose this case, I shall not have to pay by reason of the terms of the contract. I shall either win or lose. In either event I shall not have to pay."