Beyond the Barrier

From the front flap of the Doubleday first edition: "Gordon Naismith was a physics professor at a large California university. The year was 1980, and by means of the university's duplicator he could personally teach in nine different classrooms simultaneously. Naismith was an average man in all but two respects: the reflexes were extraordinarily quick, and four years before in a plane crash he had lost all memory of his earlier life. Neither difference seemed important until one day a very unusual student in one of his classes asked a disturbing, extracurricular question: "Professor, what is a zug?" The question triggered a series of violent incidents, and soon Naismith himself, as well as the police, were beginning to wonder if the duplicator had reproduced him a tenth time. The answer lay ten thousand years in the future."