A professor of philosophy brought shaving cream, toothpaste, and some other items in tubes to his class. He gave an item each to every student and asked them to empty the tubes onto their desk.
Obviously, students rushed to do it with joy and had lots of fun. Once all the tubes were empty, the teacher then asked students to put everything back inside the tubes.
Naturally, it is impossible to do so and most of the students did not even try to do it. The professor said to them:
“At the time you were so focused that you were not even trying to realize the damage you were doing. The damage has spread rapidly and it is impossible to put it all inside. Remember that when you have to get out the words of your mouth …”