Ignorance is a natural human state. The limits on what creatures of other species can know are not the limits of the universe; our species is unlikely to be very different. Our knowledge stands in more need of explanation than does our ignorance. Self-knowledge is no exception. We do not expect creatures of other species to be capable of knowing everything about themselves; we should not expect to be capable of knowing everything about ourselves. The same applies to our knowledge of our own creations. In some sense we create our language, but it does not follow that it is in every respect open to our gaze. Why should the boundaries of our terms not be invisible to us?