It is merely, I said a matching of the prisoner’s intellect with that of his opponent.
It is, said Dupin.
And, when I asked the boy how he did this, he answered, when I want to find out how stupid, or how wise, or even how good or wicked a person is, or even what he is thinking at the moment, I match the expression on my face as closely as I can to the expression on his face.
Then I wait to see what thoughts or feelings occur in my mind or heart.