XIV
"Leave the fire alone," Charles said sharply to Kennedy. The little man was going to douse it for the night.
There was a flash of terrified sense: "They beat you. If the fire's on after dark they beat you. Fire and dark are equal and opposite." He began to smile. "Fire is the negative of dark. You just change the sign, in effect rotate it through 180 degrees. But to rotate it through 180 degrees you have to first rotate it through one degree. And to rotate it through one degree you first have to rotate it through half a degree." He was beaming now, having forgotten all about the fire. Charles banked it with utmost care, heaping a couple of flat stones for a chimney that would preserve the life of one glowing coal invisibly.
He stretched out on the sand, one hand on the little heap b
