The most stirring moments come when one person's hour ends in the video and another's begins. The frenetic pace of the film slows as a new person enters with measured steps from the side and lines up face forward behind the person already there: a bulky man behind a slight woman, a short man behind a tall one. Each arrival gently lays a hand on the shoulder of the one already there, and at that moment, the film almost stops, as if holding its breath. Then the front performer, responding to the touch, turns and slowly walks out of the picture.

Only after you watch this passing of energy a few times do you start to figure out what you're really seeing: a ritual dance, a morality play and a mortality play. The story is primal. It's about being singular and at home in the world at the same time, and how difficult, but possible, that is. The homeless people in "Endurance" are living the story. The collaboration with Mr. McCallum and Ms. Tarry gives them a chance to perform it - that's the art part, the distancing and clarifying part - and lets us participate as witnesses.