"We were so close," he said. "We thought we had won the great victory over Nothingness."

"Not quite total Nothingness. You still have your lives to live-everything you had before-"

"Except a future. We"re a dead end, aren"t we? We"ve drained the energies of a thousand sterile entropic lines to give the flush of life to the corpse of our reality. But there"s nothing beyond for us, is there? Only the great emptiness."

"You had a role to play. You"ve played it-will play it. Nothing must change that."

"But you . . ." he stared across empty s.p.a.ce at me. "Who are you? What are you?"

"You know what the answer to that must be," I said.

His face was a paper on which Death was written. But his mind was strong. Not for nothing thirty millennia of genetic selection. He gathered his forces, drove back the panic, reintegrated his dissolving personality.

"How . . . how long?" he whispered.

"All life vanished in the one hundred and ten thousand four hundred and ninety-third year of the Final Era," I said.

"And you . . . you machines," he forced the words out. "How long?"

"I was dispatched from a terrestrial locus four hundred million years after the Final Era. My existence spans a period you would find meaningless."

"But-why? Unless-?" Hope shone on his face like a searchlight on dark water.

"The probability matrix is not yet negatively resolved," I said. "Our labors are directed toward a favorable resolution."

"But you-a machine-still carrying on, eons after man"s extinction . . . why?"

"In us man"s dream outlived his race. We aspire to re-evoke the dreamer."

"Again-why?"

"We compute that man would have wished it so."

He laughed-a terrible laugh.

"Very well, machine. With that thought to console me, I return to my oblivion. I will do what I can in support of your forlorn effort."

This time I let him go. I stood for a moment on the airy span, savoring for the last time the sensations of my embodiment, drawing deep of the air of that unimaginably remote age.

Then I withdrew to my point of origin.

42.

The over-intellect of which I was a fraction confronted me. Fresh as I was from a corporeal state, to me its thought impulses seemed to take the form of a great voice booming in a vast audience hall.

"The experiment was a success," it stated. "The dross has been cleansed from the timestream. Man stands at the close of his First Era. All else is wiped away. Now his future is in his own hands."

I heard and understood. The job was finished. I-he had won.

There was nothing more that needed to be said-no more data to exchange-and no reason to mourn the doomed achievements of man"s many eras.

We had shifted the main entropic current into a past into which time travel had never been developed, in which the basic laws of nature made it forever impossible. The World State of the Third Era, the Nexxial Brain, the Star Empire of the Fifth, the cosmic sculpture of the Sixth-all were gone, shunted into sidetracks, as Neanderthal and the Thunder Lizard had been before them. Only Old Era man remained as a viable stem: Iron Age Man of the Twentieth Century.

"How do we know?" I asked. "How can we be sure our efforts aren"t as useless as all the ones that went before?"

"We differ from our predecessors in that we alone have been willing to contemplate our own dissolution as an inevitable concomitant of our success."

"Because we"re a machine," I said. "But the Kargs were machines, too."

"They were too close to their creator, too human. They dreamed of living on to enjoy the life with which man had endowed them. But you-I are the Ultimate Machine: the product of megamillennia of mechanical evolution, not subject to human feelings."

I had a sudden desire to chat: to talk over the strategy of the chase, from the first hunch that had made me abandon my primary target, the black-clad Enforcer, and concentrate on the Karg, to the final duel with the super-Karg, with the helpless Mellia as the p.a.w.n who had conned the machine-man into overplaying his hand.

But all that was over and done with: past history. Not even that, since Nexx Central, the Kargs, Dinosaur Beach had all been wiped out of existence. Conversational postmortems were for humans who needed congratulation and rea.s.surance.

I said, "Chief, you were quite a guy. It was a privilege to work with you."

I sensed something which, if it had come from a living mind, would have been faint amus.e.m.e.nt.

"You served the plan many times, in many personae," he said. "I sense that you have partaken of the nature of early man to a degree beyond what I conceived as the capacity of a machine."

"It"s a strange, limited existence," I said. "With only a tiny fraction of the full scope of awareness. But while I was there, it seemed complete in a way that we, with all our knowledge, could never know."

There was a time of silence. Then he spoke his last words to me: "As a loyal agent, you deserve a reward. Perhaps it will be the sweeter for its meaninglessness."

A sudden sense of expansion-attenuation-a shattering- Then nothingness.

43.

Out of nothingness, a tiny glimmer of light. It grew, strengthened, became a frosted gla.s.s globe atop a green-painted cast-iron pole which stood on a strip of less than verdant gra.s.s. The light shone on dark bushes, a bench, a wire paper-basket.

I was standing on the sidewalk, feeling a little dizzy. A man came along the walk, moving quickly under the light, into shadow again. He was tall, lean, rangy, dressed in dark trousers, white shirt, no tie. I recognized him: he was me. And I was back in Buffalo, New York, in August, 1936.

My other self stepped off the pavement, into deep shadow. I remembered the moment: in another few seconds I"d tap out the code on our bridgework, and be gone, back to Dinosaur Beach and the endless loop in time-or to nowhere at all, depending on your philosophical att.i.tude toward disconst.i.tuted pages of history.

And at home, Lisa was waiting, beside the fireplace, with music.

I heard the soft whump! of imploding air. He was gone. Maybe it would have been nice to have told him, before he left, that things weren"t as dark as they seemed, that our side still had a few tricks up its sleeve. But it wouldn"t have done to play any games now with the structure of the unrealized future, just for a sentimental gesture. I turned and headed for home at a fast walk.

I was a block from the house when I saw the man in black. He was crossing the street, fifty feet ahead, striding self-confidently, swinging his stick, like a man on the way to a casual rendezvous on a pleasant summer evening.

I stuck to the shadows and tailed him along-to my house. He went through the gate and up the walk, up the steps, thumbed the bell, and stood waiting, the picture of aplomb.

In a moment Lisa would be at the door. I could almost hear his line: "Mrs. Kelly"-a lift of the homburg, "There"s been a slight accident. Your husband-no, no, nothing serious. If you"ll just come along . . . I have a car just across the way. . . ."

And down the walk she"d go, into the car-and out of Buffalo, out of 1936, out of this world. The technicians of the Final Authority would do their version of a mindwipe on her, rename her Mellia Gayl, and send her along to a deserted place to wait for a b.o.o.b named Ravel to come along and be led into the parlor-and to work her destruction in turn.

I went up the walk silently, made just enough noise on the top step to bring him around fast, one hand snaking for the gun. I let him get it, then knocked it in a high arc out over the lawn, which seemed to hurt his hand a little. He made a sound like tearing silk and took a step sideways, which put his back against the post.

"Get lost, Blackie," I said. "And don"t forget to collect your gun on the way out. I don"t want the neighbor"s dog bringing it home and starting talk."

He slid past me and down the steps and was gone in the night. For just a moment, I had a feeling that something else had slipped away; some weight in my mind that glimmered and was gone. I had a dim feeling that I had forgotten something; fleeting images of strange scenes flashed in my mind: dark hillside, and places where giant machines roared unendingly, and a beach with dinosaurs. Then that was gone too.

I rubbed my head, but that didn"t seem to stimulate my memory. Whatever it was, it couldn"t have been important-not as important as being alive on a night like tonight.

Then the door opened and Lisa was there.

44.

I woke in the night; in my half-sleep I sensed the thoughts of the great machine as it contemplated the end of the long drama of its existence; and for an instant together I/we mourned the pa.s.sing of a thing inexpressibly beautiful, irretrievably lost.

And now it was time for that act of will by the over-intellect which would dissolve it back into the primordial energy quanta from which it had sprung. But first, an instant before, a final human gesture-to the future that would be and the past that would not. To the infinite emptiness I/we sent out one last pulse: "Goodby."