From The Book of Illusions by Paul Auster

After the main character receives an unusual letter:”I read it six or seven times. Then I put it down, walked to the other end of the room, and came back. When I picked up the letter again, I wasn’t sure if the words would still be there. Or, if they were there, if they would still be the same words. I read it six or seven more times, and then, still not sure of anything, dismissed it as a prank. A moment later, I was filled with doubts, and the next moment after that I began to doubt those doubts. To think one thought meant thinking the opposite thought, and no sooner did that second thought destroy the first thought than a third thought rose up to destroy the second.” via /r/bookquotes http://ift.tt/2sDsszi