In Ancient Greece, Socrates had a great reputation of wisdom. One day, someone came to find the great philosopher and said to him:

- Do you know what I just heard about your friend?

- A moment, replied Socrates. Before you tell me, I would like to test what you might say with the three sieves.

- The three sieves?

- Yes, continued Socrates. Before telling anything about the others, it's good to take the time to filter what you mean. I call it the test of the three sieves. The first sieve is the TRUTH. Have you checked if what you're going to tell me is true?

- No, I just heard it.

- Very good! So, you don't know if it's true. We continue with the second sieve, that of KINDNESS. What you want to tell me about my friend, is it good?

- Oh, no! On the contrary.

- So, questioned Socrates, you want to tell me bad things about him and you're not even sure they're true? Maybe you can still pass the test of the third sieve, that of UTILITY. Is it useful that I know what you're going to tell me about this friend?

- No, really.

- So, concluded Socrates, what you were going to tell me is neither true, nor good, nor useful. Why, then, did you want to tell me this?