From Eric Ambler’s The Mask of Dimitrios:

Only a few men, painters, have been able to see the mind through the face. Other men in their judgements reach out for the evidence of word and deed that will explain the mask before their eyes. Yet, though they understand instinctively that the mask cannot be the man behind it; they are generally shocked by a demonstration of the fact. The duplicity of others must always be shocking when one is unconscious of one’s own.