Self-deception is not only believing what is untrue... it is also not believing what is true.
Self-deception is essential to being persuasive. When a person cannot deceive himself the chances are against his being able to deceive other people.
Self-deception is baked into the very nature of language and of thinking. Whenever a man talks he lies, thinking is self-dialogue, so therefore whenever we think we lie.
Self-deception is as easy to perpetrate without perceiving it oneself as it is difficult to deceive others without their finding out.
Self-deception is lying to yourself and listentening to your own lie such that you cease to be capable of distinguishing the truth within you.
Self-deception is lying to ourselves, and lying to ourselves is more deeply ingrained than lying to others.
Self-deception is man's curse of thinking so intently about what he thinks he is that he overlooks what he indubitably ought to be.