They had stepped clear out to the edge of the galaxy, where the fringing stars were lost in the outer void and the dead suns swept forever through the entombing dark, where even the memory of creation was gone, blotted out by unimaginable time. No delimited frontier was here, but a border region between the swarming star-sparks and the black abyss beyond. Trehearne tried to remember how long it had been since they had taken off from Thuvis. He couldn't. Time seemed oddly elastic when you lost all the familiar frames of reference. He gave it up. It didn't matter. He peered with aching bloodshot eyes into the lightless seas that lie beyond the island universes and tried to remember why he had come here. And that too was dim in his mind. Edri was bent over a table that had been set up in the bridge. He no longer looked like Edri. He seemed to have been working for a million years. Arrin sat near him. He held his head between his bony hands, a bearded mummy embalmed upright, hardly retaining the semblance of life. There were charts under Edri's hands, endless sheets of calculations and graphs, endless miles of figures. Joris studied them, bending beside Edri. His broad jowls hung down now over his wrinkled collar. His eyes had sunk deep under ridges of bone, peering out as from two shadowed caves. Edri was talking in a voice that came from far away. The words reached Trehearne in droning snatches from beyond the fog of weariness. "--so our only way to locate Orthis' ship was to triangulate its position from two separate bearings on it. One bearing was the course of that life-skiff Orthis sent in with his last message, allowing for aberrations caused by the gravitational field of stars. The other bearing was Orthis' course in his last flight. We couldn't get that till I found the part of the Lankar manuscript that Arrin didn't have." Trehearne heard someone ask, "Who was Lankar?" "One of Orthis' last pursuers, who left a secret log of the pursuit to ease his guilty conscience. Enough of it survived--" Joris said, "The hell with Lankar. Get on with it." "We had to push the star-maps back in time--galactic motion, star streaming, a million complicated problems of relative motion and proper motion, back five hundred years and then another five hundred, and then correlate them. Handling an almost unlimited number of variables like that, it could only be done on the biggest math-machines and electronic computers at Llyrdis. And that meant it all had to be done secretly, bit by bit. That work's been going on for a long, long time." Edri drew a long breath that was coupled with a racking yawn.