There was once a poor peasant named Crabb. He sold a load of wood to a doctor for two thalers. While receiving payment, he saw the doctor dining elegantly and wished to become a doctor himself.
He asked the doctor how to become one. The doctor told him to: 1) Buy an ABC book with a rooster on the cover; 2) Sell his cart and oxen to buy proper clothes and medical supplies; 3) Paint a sign saying "I am Doctor Knowall" and nail it above his door.
Crabb did as instructed. Soon after, a rich lord had money stolen and heard of Doctor Knowall. He fetched Crabb and his wife, Grethe, to his castle for dinner.
As the first servant brought a dish, Crabb nudged his wife and said, "Grethe, that was the first," meaning the first servant. The servant, who was the first thief, thought he'd been exposed and panicked. The same happened with the second and third servants.
The fourth servant brought a covered dish. The lord asked Crabb to guess its contents. Crabb, clueless, sighed, "Ah, poor Crabb." The lord exclaimed, "He knows who has the money!"
The terrified servants confessed to Crabb, offered to return the money plus a reward, and led him to its hiding place.
Satisfied, Crabb returned to the table, opened his ABC book, and pretended to search. A fifth servant hid in the stove to eavesdrop. Unable to find the rooster picture immediately, Crabb muttered, "I know you are there, so you had better show yourself." The hidden servant, thinking he was discovered, jumped out in terror, crying, "That man knows everything!"
Doctor Knowall revealed the money's location without naming the thieves. He received rewards from both the lord and the servants and became a renowned man.