A young man asked Socrates to teach him the technique of lecturing. In order to show that he was an eloquent speaker, the young man talked on and on about all irrelevant matters.
“You should pay me double the tuition fee.” said Socrates.
“Why? Why should I pay double?” the young man said with a surprise.
“Because,” Socrates said humorously, “I must teach you two courses: one is how to close your mouth, the other is how to lecture.”