One day a man met Socrates and said, "Do you know what I just heard about your friend?" "1a minute," Socrates replied. "Before you talk to me about2friend, it might be a good idea to take a moment to filter (过滤) what you're going to3. I call it Three Filter Test. The first filter is Truth. Have you made absolutely4that what you are about to tell me is true?" "Well, no," the man said. "5I just heard about it and…" "All right," said Socrates. "So you don't really know whether it's true or not. Now, let's try the second filter, the filter of 6. Is what you are about to tell me about my friend7good?" "No, on the contrary…" "So," Socrates continued, "you want to tell me something bad about my friend, but you're not certain it's true. You may8pass the test though, because there's one filter left—the filter of Usefulness. Is what you want to tell me about my friend going to be9to me?" "No, not really." "well," concluded Socrates, " if what you want to tell me10true, nor good, nor even useful, why tell it to me at all?"