Interesting. I don't believe he actually defined "truth." Leaving that term undefined muddies the discussion. In the words of Robin Williams, "Reality. What a concept." Perceptual scientists have told us for years that senses are filtered by emotional states, other sensory cues, what we are mentally prepared to understand. There may be a hard and fast thing that is reality. We are seldom in direct touch with it. Now if the subject is intentionally manipulated presentation of physical events, the conversation becomes something entirely different. Even then, the produced image may be "real"-- again, depending on the definition of the first term.