Socrates was famous for his knowledge(学问). One day, a man went up to him and said. "Do you know what I just heard about your friend, Chaerephon?"
"Hold on a minute," Socrates said. "Before telling me anything, I'd like you to pass a little test(测试). It's called the 'triple filter(过滤) test'."
"Triple filter?"
"That's right," Socrates said. "Before you talk to me about my friend, it may be a good idea to think about what you're going to say. The first 'filter' is truth. Are you sure what you are going to tell me is true?"
"In fact, I just heard about it and…" the man said.
"All right," Socrates said. "So you don't really know whether it's true or not. Now let's try the second filter--goodness. Is what you are going to tell me something good?"
"No," the man answered.
"OK," Socrates said, "one filter left--usefulness. Is what you want to say useful to me?"
"No, not really," the man said.
"Well," Socrates said, "if what you want to say is not true, good or useful, why tell it to me?"
① usefulness ②truth ③goodness