How does the words ‘Thou turn ‘st mine eyes into my very soul’ show that Hamlet is succeeding in his goal

Hamlet is berating his mother pretty badly here. He is comparing his goodly father to the snake that is his Uncle Caludius. Gertrude is obviously affected by Hamlet's rebuke. She says that she is looking inward to her own soul, And there I see such black and grainèd spots. As will not leave their tinct.