"That it doesn't strike us at all when we look around us, move about in space, feel our own bodies, shows how natural these things are to us. We do not notice that we see space perspectively or that our visual field is in some sense blurred towards the edges. It doesn't strike us and never can strike us because it is the way we perceive. We never give it a thought and it's impossible we should, since there is nothing that contrasts with the form of our world. What I wanted to say is it's strange that those who ascribe reality only to things and not to our ideas move about so unquestioningly in the world as idea and never long to escape from it."
See also: Hidden in Plain Sight All Around Us