Read the following fable by Aesop.
The Miller, His Son, and the Donkey
One day a miller and his son walked their donkey to market. The miller wanted to sell the donkey, so he led the animal slowly. He thought he would get a better price if it was in good condition.
They soon met a traveler. "What fools!" the traveler said, laughing. "Why walk the donkey when you could ride it?"
The miller hated being laughed at, so he told his son to ride the donkey.
They met three traders. "Show respect, boy!" the traders called. "Let the old man ride."
The miller didn't want the traders to think his son didn't respect him. His son got down, and he rode the donkey himself.
They passed two women. "Look at that fool!" one woman cried. "He rides the donkey, while the poor boy walks."
The woman's words upset the miller, so he told his son to climb on and ride with him.
They passed two farmers. "That poor animal!" one yelled. "It can barely carry you. It would be easier for you to carry it!"
The miller and his son got off the donkey. Using some rope, they tied the donkey to a pole and carried it.
Just as they were crossing a bridge, the rope broke. The donkey fell into the river below.
What is the main theme or lesson of the fable?