Thus acquaintance of one group with another is not enough in itself to break down prejudice, for the white man may see the Negro, or the Christian the Jew, not as the other really is but as he thinks the other group ought to be. Only escape from group thinking, the use of the individual intelligence about an individual, can possibly make any difference in our pre-conceived notions of other peoples. Moreover it is true, as Professor Shailer of Harvard pointed out long ago in his book, “The Neighbor,” that this fact of difference operates most strongly when the two different groups come into contact with each other. Prejudice is always strongest on the frontier. The Nebraskan does not have the active prejudice against Mexico that animates the Texan, nor against Japan that we find in California, nor against the Negro as in the solid south. Not that Nebraska is a land favored peculiarly by justice, but that it has no direct contact with large numbers of these different races. Naturally, this contact often opens the way to real acquaintance, before which intolerance grows faint and may even vanish. American soldiers in the occupied districts of Germany brought enough German brides to show how quickly prejudice breaks down on personal acquaintance. Christian scholars of the time of Humanism learned Hebrew from Jews whom their medieval predecessors would have avoided as the plague, and a new respect for Judaism began to spread. But as long as the contact of the two peoples is a frontier contact only, a group contact, of class with class, directed by their different status in the world, such contact merely ministers to the intolerance which individual knowledge and friendship would break down. A striking instance of this group nature of intolerance occurred within my own observation on the Western front during the World War. In an attack one of our prisoners was a German lad of eighteen, a harmless peasant boy who had deserted his machine gun and come in willingly as a prisoner; we made him useful about the first aid post, and he carried water, swept out the place, and even wrapped up German helmets to send to America as souvenirs. But Hans had been a machine gunner; if our soldiers had found him at his post they might have shot him on sight. If they had found him with other troops, they would have disarmed him, driven him back to the prison camp. In the first case, he would have belonged to the group of machine gunners, the greatest danger to the American advance. In the second, he would have belonged to the group of German soldiers, and been fair prey for enmity and capture. As it was, he was regarded merely as Hans—and the hated German machine gunner acted as servant to the friendly American bosses.