“For once a thing is known, it can never be unknown. It can only be forgotten.”
“And for once, Donald Rumsfeld, in the news at the time over the Iraq war made sense to me: "As we know," he said, famously, "there are known knowns-things we know we know. We also know there are known unknowns-things we know we don't know. But there are also unknown unknowns- things we don't know we don't know.”
“Only the unknown frightens men. But once a man has faced the unknown, that terror becomes the known.”
“There are things known and there are things unknown, and in between are the doors of perception.”
“In the universe, there are things that are known, and things that are unknown, and in between, there are doors.”