The image that we have of ourself is based on our memories, those related to our personal behavior, our relationships, our successes and our failures. Of course, our self image is also influenced by early childhood experiences (which we cannot recall) and by suppressed memories (too painful to dredge up).
Then again, studies suggest that our memories are malleable, subject to alteration when repeatedly called up and re-stored. Nevertheless, our self image is governed by this unreliable script of vague events and interactions from our past.
Do we really know ourself? Perhaps more importantly: do we judge ourself fairly?