Biblical verse Jeremiah 5:21 "Hear now this, O foolish people, and without understanding; who have eyes, and see not; who have ears, and hear not".
Indeed: "there are none so blind as those who will not see and none so deaf as those who do not hear & listen."
Ostriches used to be able to fly until someone sneaked up on them and clipped their wings. I wonder how they managed to do that?