The flash of light from the rack of surveillance cameras above us signals that our pictures have been taken as we enter the Yăyè Expressway, passing through the mountainous Garzê Tibetan Prefecture of Sìchuān. We are on our way back to Chéngdū, and manage to see only brief glimpses of the mountain countryside inbetween the endless series of long, long tunnels. The driver begins to recite a chant from memory — or is it improvised? Is it a practice simply to keep awake — the road is long — or is it a kind of prayer?