To the uninitiated, it didn't look like much of a temple. A cinder-block proscenium, painted toothpaste green, fronting a sort of glorified barbeque pit behind which the priest stood. But the temple, in a small village northwest of Bangalore in southern India, was holy for many of the villages in the area, and on that Saturday afternoon, the Hindu faithful flocked to do puja. Sari-clad women rolled in the dust outside, prostrating themselves.

At the entrance, two wizened men stood beating buffalo-skin drums. They summoned the faithful with their drums, but were barred from entry themselves, as they were Dalits, as members of the Untouchable caste now call themselves. They stood in their ragged dhotis, playing drums--instruments of the Untouchables, traditionally barred from playing horns and strings to make music, and therefore confined to making music with animal skins.

The two men set the momentum of the moment--the sheep and chickens were slaughtered to their beat, the women stepped over the pools of animal blood to ask for priest blessings to their music--but the two men had to stop at the door. India's 160 million Dalits are barred from most Hindu temples, as they are believed to be polluting influences.

"What caste are you?" the hard-eyed temple priest asked me as I stepped across the temple threshold, oblivious to my conspicuously non-Hindu features.

Caste is, if not all, then at least crucial in India. Scan the Matrimonials section in the Sunday papers, and you'll find just a tiny fraction of the entries contain the phrase, "Caste no bar," welcoming applicants from a range of castes. Far more common are entries like "Extremely handsome North Indian, Brahmin . Manager with India's largest Petrochemical Co., . Proposals invited from extremely good looking professionally qualified girls."

It's not just the Hindus who practice caste: the brutally efficient ranking system has crept into South Asia's Christian and Muslim cultures. Until recently, there were tales of separate communion cups for Untouchable converts to Christianity, lest they pollute the rest of the congregation; even today, there's a Christian burial ground in Trichy, South India, where the Dalit souls are laid to rest separately from God's other children.

At the temple, children stared at the real outcasts--the two foreign women with their Nikons and notebooks, the two Dalits grinned, snaggle-toothed and not altogether subservient. They pounded away, making music out of rage, shoving their drums near the pious and curious, who relented by shoving crumpled ruppee notes at them.

The two men weren't allowed in the temple, but knew that the temple business, on that afternoon, rested on their being there-and not there. They were crucial for that hoary old ploy of making the sacred by exclusion: of drawing a line in the sand, and keeping some people out, creating a man-made holiness.