There are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns - the ones we don't know we don't know.
Madness string 81577
White birds soar against the bright blue sky, flapping their wings like rippling waves, wavering in shades of bright and shadow, all odd. An illusion of separation, above and below, pushed aside in each flap, each swoop, each interweaving motion of the flock...