Can Someone Explain To Me The Whole Endurance Thing?

So I tuned in for bits of the David Blaine thing last night, and obviously however many people packed the plaza at Lincoln Center get it, and I will say this: I think his magic is really really cool. Ben and I kind of broke it down last night – he does stuff that’s small enough to be believable, but unusual and strange enough to truly be amazing. Also half the fun is he does it in public places and the reaction of the people seems to range very humorously from freaked out to really freaked out. BUT. The Houdini thing, I’m not so sure I really get. Something about a test of endurance and human will versus the body and even the mind. Except a) I feel like I know people are incredibly resilient in many ways, when they need to be, like I just read part of DFW’s essay about McCain’s POW years which kind of blew my mind – I had known about it of course, but not all the specifics, which are beyond horrific, the critical difference between him and Blaine being: Blaine has a choice. And plus b) I feel like I already know as much as I ever want to from endurance. So it’s the whole choice thing that baffles me. It’s about proving something we already know?