King Duncan says Theres no art to find the minds construction in the face. He was a gentleman on whom I built an absolute trust (Act 1, Scene 4). Duncan was referring to the (now-executed) Thane of Cawdor, whom he trusted and who betrayed that trust. But then Duncan immediately does exactly the same thing with Macbeth trusts him completely. And Macbeth, as we know, is about to betray Duncans trust, in the worst way possible. Is Duncan naive?