BORDER POST OF ETERNITY Robotic minds made interstellar travel possible, but human minds still controlled the destination and purpose of such flight. Conflict develops only when a programmed brain cannot evaluate beyond what is visible and substantial, whereas the human mind is capable of infinite imagination - including that which is unreal. Such was the problem at the singularity in space in which the ALTAIR STAR and a hundred other vessels had come to grief. At that spot, natiral laws seem subverted - and some other universe's rules impinged. For Buchanan, the station meant a chance to observe and maybe rescue his lost vessel. For the robotic navigators of oncoming spaceships, the meaning was different. And at Singularity Station the only inevitable was conflict.