Sean Carroll (the cosmologist SC, not the biologist) talks about the big mysteries:
...the origin of the universe, the origin of life, and the origin of consciousness.
He includes a short clip of Ed Witten discussing the mystery of consciousness. He thinks it's a tough one, but this was the first time I had heard him speak, and that was pretty interesting in and of itself. He definitely doesn't sound like the guy next door.
It might be that I'm just too dumb to appreciate how mysterious consciousness is, but I don't share the kind of mystical feeling about it that guys like Witten, Scott Aaronson, and Roger Penrose have. For one thing, I doubt that human consciousness is very different from animal consciousness.
I used to have a baby turtle that needed to eat live food, and I fed it meal worms that had been kept in the refrigerator. For the most part they went softly into that good night, but sometimes they managed to escape and warm up, sometimes turning into beetles that flew away, but other times encountering the turtle in a warmed up and wide awake state. I found it pretty easy to map their reactions and frantic efforts to escape into my own "oh shit" moments.
I found it pretty disquieting.