Are We Dreaming When We Think We're Seeing?

"What can socrates be sure of? This is what hermes is pressing him on. It seems to me you've been asking questions about me, what is in front of me, what i can easily see, whether i am sure and so on," xenophanes writes. "I estimate that not a single one of them is predominantly about me", he adds. 'Perhaps this entire vision of you is not a dream after all, but some cunning conjurer's trick'