When the night came the barbarians were still holding. Tomorrow, Xerxes thought, his troops would be victorious. Tomorrow came and fresh troops went forth. And eventually the news came back to where Xerxes waited that his army had been routed and was fleeing in disorder. It was fate, Xerxes perhaps decided. Fate was a chancy thing. No man could know for certain what the morrow would bring. Tomorrow was a dark reality and the paths to the future were uncertain and tortuous. But if Xerxes had ravaged the peninsula of Greece in 480 B.C. in all probability Plato would not have been born in 427, and he would not have had as his pupil a youth named Aristotle, and the thinking of the scientists of twenty-five coming centuries would have lacked the guidance of these two men. Into the dark reality of the future the human race would have followed other paths and the man-world of 1940 would not have come into being. There is a pass in Greece called Thermopylae. * * * * * Lee Garth watched, his eyes following the pencil. Cold winds seemed to blow on him. They blew colder each time he realized he was not dictating what the pencil was writing. He watched the factors appear on the paper. There was a meaning in those symbols, a meaning and a purpose stretching across the long, long gulfs of time, reaching from the amoeba, in the protoplasmic slime of steaming seas that are long gone, forward to the creature that shall emerge in some other era, in some century of the far future. Through him the meaning ran, through Lee Garth, who was 37 years old in 1940. * * * * * There is a field in France. The far-flung southern horn of the Saracen crescent, sweeping northward in its history changing flight, found the field in France where Charles Martel--Charles the Hammer--waited. With keen sword, and long lance, and hissing arrow, all day long the armies battled, and when the night came on, the Saracen host, smashed and bleeding under the blows of the Hammer, reeled backward, fled back out of France. To the Saracens, tomorrow and tomorrow and tomorrow, was the backward turning road. The glowing sun of Islam flickered, and never again burned so brightly. There was a shift in history, and another world evolved because of Charles Martel. There is a field in France called Tours. Lee Garth mopped the perspiration from his forehead. He stopped writing for a moment, pushed back his thinning hair, pulled a cigarette from the package on his desk, struck a match. The smoke was blue and indistinct in that shadowed room. Far off, from another world it seemed, there came the raucous hoot of an automobile horn. Somebody going home, or going to work, or going somewhere but probably going home, since the hour was so late. Didn't matter. There was a gadfly buzzing in his brain. Again the pencil raced over the paper. * * * * *