The story above has a true moral, evident only if the story is told in its entirety..

...When the murmur of agreement subsided, a student raised his hand confidently. The professor asked what the student had to add, to which the student replied that he had a similar practical addition to make and had to approach the desk to provide his contribution.

Upon reaching the professor's desk, he took a beer-can from his pocket, opened it with a flourish, and proceeded to pour beer into the jar, truly filling the remaining spaces with beer. Turning to the class, the expression on the students' faces was enough to confirm that now the jar was truly filled.

The moral is therefore amended to : No matter what your life is full of, there is always room for beer.