In memory of Walter M. Miller Jr., author of the science-fiction classic, "A Canticle for Leibowitz."

Brother Erasmus might never have found the Lost Gospel had it not been for the pilgrim with girded loins who'd approached him in the wilderness. The monk was well into his fast in honor of the blessed St. Lysenko when his peace was disturbed.

Never before had Brother Erasmus actually seen a pilgrim with girded loins, but this one had to be the bona fide article. You could see him, and soon enough smell him, hobbling across the still slightly radioactive wasteland. And what an unsettling apparition he was: a spindly old fellow with a staff, basket hat, brushy beard, and a waterskin slung over one shoulder.

The old boy wasn't armed, so he couldn't be one of the highwaymen who covered the countryside. And he had only one head, which ruled out his being one of the mutants that roamed at night. He must be one of the few if any religious left.

Imagine that. Erasmus had assumed that all the Old Believers had been hunted down by the survivors of the Last World War. The massacres had begun during the Great Secularization, when people had realized how the old, divisive ideas had caused the final cataclysm. Most of the religious had been burned at the stake, along with the books that had spread their dangerous ideas. That should have been the end of their baneful influence. But here was one more false prophet.

The Darwinian order to which Brother Erasmus belonged taught only pure science at abbeys like his own, and no one was allowed to question it, lest the Dark Ages return. Those certified to teach the young were not allowed to question Darwin's revelation, and certainly not present alternate theories. That way lay division and dissent and, inevitably, fiery chaos.

People had forgotten the old superstitions, yet here came this remaining fanatic out of a distant past. Now he was shouting something in a long forgotten tongue: Ego te absolvo! The phrase had something to do with forgiveness, as best Erasmus could remember from Archaic Studies 101.

Forgive this, Erasmus thought as he reached for his trusty bow. The old man was not more than 20 yards away when the arrow hit him squarely between the eyes. Call it natural selection.

The pilgrim was breathing his last by the time Erasmus reached him and began to go through his belongings. There was nothing much there. Then he noticed the little book he would eventually come to think of as the Lost Gospel. It was entitled "Recapitulation and Conclusion," and it was the strangest thing he'd ever read, at least in Old English. It was written as if it were the last chapter of "The Origin of Species" itself, mocking the style of Darwin Our Deliverer, blessed be his name.

Brother Erasmus knew he should have burned the forgery then and there, but even the best of us are sore beset by temptation. He began to read: "I see no good reason why the views given in this volume should shock the religious feelings of any one."

Well, Brother Erasmus was shocked. No one had ever showed him such a passage before in holy writ. He could not resist reading the whole thing - to the very last sentence:

"There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."

Amen, Erasmus heard himself murmur before thinking. That was when he realized how subversive was the document he held in his hands. Not knowing how to do penance, he did nothing. Finishing up his sojourn in the wilderness, he kept reading and re-reading the little book, struggling to hold on to his pure materialist faith till he could get back to the monastery and confess to the abbot.

But he never did. He knew the tattered old book was a fake, but he couldn't stop thinking about that last passage. He told himself that, if sainted Darwin had actually written it, then even Our Teacher could err, and it was only fitting that the Holy Infallible College of Scientists had suppressed it.

Nevertheless, one small detail kept nagging at him, petty and irrational as it was. Maybe it was only a typographical error, reverently repeated in each faithful reprinting of the Origin. It was that single capital C with which our Darwin had spelled Creator - as if it were a proper noun, as if there were a Person involved, and if there was a Person, all this had to be personal, and then.

He dared not go further. Instead he concentrated on his calligraphy, telling himself that his dangerous, primitive thoughts would evolve away. But he could not exorcise the heretical words. They seemed to be leading him somewhere.

Erasmus had silenced the old man to preserve the peace that surpasseth all faith. But ever since, he'd had the strangest mix of sensations. Not just guilt but something bright and hopeful beyond it, something like forgiveness, acceptance, love.

One night Erasmus could no longer keep his heretical thoughts at bay. He wrapped up the Lost Gospel to take with him, where he knew not, took some bread and wine from the common table, girded up his loins, and set out on his wanderings.