"Perhaps we wouldn't be far wrong if we thought of the Sweeneys as catalysts!" he said.
Cynthia stood very straight and quiet, a great fear growing in her.
"Catalysts, Ned?"
"It's just a wild guess, of course. I can't even tell you what made me think of it. But it does have a certain relevancy. In chemistry, as you know, a catalytic agent is a substance which promotes chemical action, but is in itself unchanged."
"Well?"
"Why do men and women who surrender themselves to sorcery remain, in legend, eternally young? Young, unchanging. It's a belief as old as prehistory and all the ages since. Only in the Middle Ages were witches pictured as shrunken, hideous old women. The ancient world pictured witches as eternally youthful, unaging."
A long pause, and then Ned said: "As unaging as the forests of oak where they served as human catalysts for the Druids before the Druids left Earth forever?"
He suddenly seemed to be thinking aloud rather than addressing his wife.
"Well—and why not? The Druids must change, for change is the first law of life. But perhaps they can only find complete fulfillment, can only grow in wisdom and strength, by using human beings as little hard grains of chemical substance which must remain forever bright and shining.
"Human catalysts, imprisoned in a horrible little test tube of a house. If human beings aged and changed they would cease to be catalysts. They would become valueless to the Druids. And when the Romans discovered the truth—"