Corax was known as the "father of persuasion" and taught the art of forensic debate. He decided to retire and took on an apprentice named Tisias to teach him. However, after completing his teachings, Tisias refused to provide the agreed compensation. When Corax sued, Tisias argued that if he won, Corax had failed to teach him, and if he lost, Corax would owe him. This created a "heads I win, tails you lose" dilemma and is how the concept of sophistry was born.