The Warlock picked up a copper disc. "Four," he said, and the disc spun in midair.

By the time Hap had sloshed through the stream, the disc was a blur of motion. The Warlock moved to keep it between himself and Hap. and Hap dared not touch it, for it would have sheared through anything at all. He crossed around it, but again the Warlock had darted to the other side. In the pause he snatched up something else: a silvery knife, profusely inscribed.

"Whatever that is," said Hap. "it can't hurt me. No magic can affect me while I carry Glirendree."

"True enough," said the Warlock. "The disc will lose its force in a minute anyway. In the meantime, I know a secret that I would like to tell, one I could never tell to a friend."

Hap raised Glirendree above his head and. two-handed, swung it down on the disc. The sword stopped jarringly at the disc's rim.

"It's protecting you," said the Warlock. "If Glirendree hit the rim now, the recoil would knock you clear down to the village. Can't you hear the hum?"

Hap heard the whine as the disc cut the air. The tone was going up and up the scale.

"You're stalling," he said.

"That's true. So? Can it hurt you?"

"No. You were saying you knew a secret." Hap braced himself, sword raised, on one side of the disc, which now glowed red at the edge.

"I've wanted to tell someone for such a long time. A hundred and fifty years. Even Sharla doesn't know." The Warlock still stood ready to run if the swordsman should come after him. "I'd learned a little magic in those days, not much compared to what I know now, but big, showy stuff. Castles floating in the air. Dragons with golden scales. Armies turned to stone, or wiped out by lightning, instead of simple death spells. Stuff like that takes a lot of power, you know?"

"I've heard of such things."

"I did it all the time, for myself, for friends, for whoever happened to be king, or whomever I happened to be in love with. And I found that after I'd been settled for a while, the power would leave me. I'd have to move elsewhere to get it back."

The copper disc glowed bright orange with the heat of its spin. It should have fragmented, or melted, long ago.

"Then there are the dead places, the places where a warlock dares not go. Places where magic doesn't work. They tend to be rural areas, farmlands and sheep ranges, but you can find the old cities, the castles built to float which now lie tilted on their sides, the unnaturally aged bones of dragons, like huge lizards from another age.

"So I started wondering."

Hap stepped back a bit from the heat of the disc. It glowed pure white now, and it was like a sun brought to earth. Through the glare Hap had lost sight of the Warlock.

"So I built a disc like this one and set it spinning. Just a simple kinetic sorcery, but with a constant acceleration and no limit point. You know what mana is?"

"What's happening to your voice?"

"Mana is the name we give to the power behind magic." The Warlock's voice had gone weak and high.

A horrible suspicion came to Hap. The Warlock had slipped down the hill, leaving his voice behind! Hap trotted around the disc, shading his eyes from its heat.

An old man sat on the other side of the disc. His arthritic fingers, half-crippled with swollen joints, played with a rune-inscribed knife. "What I found out -oh, there you are. Well, it's too late now."

Hap raised his sword, and his sword changed.

It was a massive red demon, horned and hooved, and its teeth were in Map's right hand. It paused, deliberately, for the few seconds it took Hap to realize what had happened and to try to jerk away. Then it bit down, and the swordsman's hand was off at the wrist.

The demon reached out, slowly enough, but Hap in his surprise was unable to move. He felt the taloned fingers close his windpipe.

He felt the strength leak out of the taloned hand, and he saw surprise and dismay spread across the demon's face.

The disc exploded. All at once and nothing first, it disintegrated into a flat cloud of metallic particles and was gone, flashing away as so much meteorite dust. The light was, as lightning striking at one's feet. The sound was its thunder. The smell was vaporized copper.

The demon faded, as a chameleon fades against its background. Fading, the demon slumped to the ground in slow motion, and faded further, and was gone. When Hap reached out with his foot, he touched only dirt.

Behind Hap was a trench of burnt earth.

The spring had stopped. The rocky bottom of the stream was drying in the sun.

The Warlock's cavern had collapsed. The furnishings of the Warlock's mansion had gone crashing down into that vast pit, but the mansion itself was gone without trace.

Hap clutched his messily severed wrist, and he said, "But what happened?"

"Mana," the Warlock mumbled. He spat out a complete set of blackened teeth. "Mana. What I discovered was that the power behind magic is a natural resource, like the fertility of the soil. When you use it up, it's gone."

"But-"

"Can you see why I kept it a secret? One day all the wide world's mana will be used up. No more mana, no more magic. Do you know that Atlantis is tec-tonically unstable? Succeeding sorcerer-kings renew the spells each generation to keep the whole continent from sliding into the sea. What happens when the spells don't work any more? They couldn't possibly evacuate the whole continent in time. Kinder not to let them know."

"But...that disc."

The Warlock grinned with his empty mouth and ran his hands through snowy hair. All the hair came off in his fingers, leaving his scalp bare and mottled. "Senility is like being drunk. The disc? I told you. A kinetic sorcery with no upper limit. The disc keeps accelerating until all the mana in the locality has been used up."

Hap moved a step forward. Shock had drained half his strength. His foot came down jarringly, as if all the spring were out of his muscles.

"You tried to kill me."

The Warlock nodded. "I figured if the disc didn't explode and kill you while you were trying to go around it, Glirendree would strangle you when the constraint wore off. What are you complaining about? It cost you a hand, but you're free of Glirendree."

Hap took another step, and another. His hand was beginning to hurt, and the pain gave him strength. "Old man," he said thickly. "Two hundred years old. I can break your neck with the hand you left me. And I will."

The Warlock raised the inscribed knife.

"That won't work. No more magic." Hap slapped the Warlock's hand away and took the Warlock by his bony throat.

The Warlock's hand brushed easily aside, and came back, and up. Hap wrapped his arms around his belly and backed away with his eyes and mouth wide open. He sat down hard.

"A knife always works," said the Warlock.

"Oh," said Hap.

"I worked the metal myself, with ordinary blacksmith's tools, so the knife wouldn't crumble when the magic was gone. The runes aren't magic.

They only say-"

"Oh," said Hap. "Oh." He toppled sideways.

The Warlock lowered himself onto his back. He held the knife up and read the markings, in a language only the Brotherhood remembered.

AND THIS, TOO, SHALL PASS AWAY. It was a very old platitude, even then.

He dropped his arm back and lay looking at the sky.

Presently the blue was blotted by a shadow.

"I told you to get out of here," he whispered.

"You should have known better. What's happened to you?"

"No more youth spells. I knew I'd have to do it when the prognostics spell showed blank." He drew a ragged breath. "It was worth it. I killed Glirendree."

"Playing hero, at your age! What can I do? How can I help?"

"Get me down the hill before my heart stops. I never told you my true age-"

"I knew. The whole village knows." She pulled him to sitting position, pulled one of his arms around her neck. It felt dead. She shuddered, but she wrapped her own arm around his waist and gathered herself for the effort. "You're so thin! Come on, love. We're going to stand up." She took most of his weight onto her, and they stood up.