Quotes about Externality

C. S. Lewis was getting at this idea when he wrote, If your thoughts and passions were directly present to me, like my own, without any mark of externality or otherness, how should I distinguish them from mine?…You may reply, as a Christian, that God (and Satan) do, in fact, affect my consciousness in this direct way without signs of "externality." Yes: and the result is that most people remain ignorant of the existence of both.