The three sieves test

"Nothing astonishes men so much as common sense and plain dealing." 

- Ralph Waldo Emerson

Once upon a time in ancient Greece, one of the acquaintances of the great Greek philosopher Socrates came running and said: “Socrates, do you know what I just heard about one of your students?”

“Wait a minute”, Socrates stopped him, “Before you tell me, I would like to conduct a simple test. It is called the three sieves test.”

“Three sieves test?”

“Yes. Before you tell me anything about my student, take a moment to consider carefully what you are going to say and pour your words through special sieves.”

“The first one is the sieve of truth. Are you absolutely, without any doubt, sure that what you are about to tell me is true?”

“Well... no. Actually I heard it recently and...”

“Alright”, interrupted Socrates, “So you don’t really know if it is true or not!”

“Now, let us try the second sieve, it is called the sieve of goodness. Are you about to tell me something good about my student?”

“Well... no. On the contrary...”

“So, you want to tell me something bad about him” roared the Socrates, “Even though you are not certain if it is true or not?”

The acquaintance shrugged, embarrassed and already feeling uncomfortable.

“You may still pass the test though” said the Socrates, “Because there is a third sieve – the sieve of usefulness.”

“Is what you were to tell me about my student going to be useful to me?”

“No, not really...” said the man resignedly. 

Socrates continued his lesson, “Well, if what you want to tell me is neither true nor good nor useful, why tell me at all?”