The professor shares hot chocolate with his guests from expensive and plain cups to teach them a lesson. When they all choose the nicer cups over the plain ones, he explains that the cup does not change the quality of the hot chocolate, and that they were focused on the wrong thing. His message is that life is the hot chocolate, and jobs and status are just the cups - tools to experience life, but they do not define the quality of life. We should focus on enjoying what we have rather than concentrating only on superficial things like the cup.