Knowing What One Does Not Know

To be able to say "I don't know" with confidence, when we don't know, shows that the speaker knows exactly what she knows and what she doesn't. It is the most valuable knowledge one should acquire early and adhere to continuously. It promotes learning to the extent that it presses one to fill the gap in a hurry in order to avoid saying it too often and looking foolish. I owe this advice to Mother, who insisted that I say "I don't know" unless I know for sure that I know what I know.