" A man does not need to be a wizard to know truth from falsehood, not if he has eyes. You need only learn to read a face. Look at the eyes. The mouth. The muscles here, at the corners of the jaw, and here, where the neck joins the shoulders." He touched her lightly with two fingers. "Some liars blink. Some stare. Some look away. Some lick their lips. Many coer their mouths just before they tell a lie, as if to hide their deceit. Other signs may be more subtle, but they are always there. A false smile and a true one may look alike, but they are as different as dusk from dawn. "
― George R.R. Martin , A Feast for Crows (A Song of Ice and Fire, #4)