“Reports that say that something hasn't happened are always interesting to me, because as we know, 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.”

“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.”

“Something unknown is doing we don't know what.”

“When we say we know something in our bones, we mean we don't know yet how we know what we know. This is what we mean by "bones.”

“Surely we cannot take an open question like the supernatural and shut it with a bang, turning the key of the madhouse on all the mystics of history. You cannot take the region of the unknown and calmly say that, though you know nothing about it, you know all the gates are locked. We do not know enough about the unknown to know that it is unknowable.”

“We have always known that heedless self interest was bad morals, we now know that it is bad economics.”