Each aviator was warned that if he lost his life before he had to, he was not only squandering his own greatest treasure, but he was leaving one man less for France. This was the philosophy of the training-school. If the French were impatient with a flier who lost his life to the Germans through excess of friskiness, they were doubly so at the flier who endangered his life at school through heedlessness. "If you pull the wrong lever," they said, "you will kill a man and wreck a machine. Your country cannot afford to pay, either, for your fool mistakes." But there their dogma ended. Once the flier had learned to handle his machine, his further behavior was in the hands of American officers solely, and these, he found, were stored with several very definite ideas. The first of these--the most marked distinction between the French system and the American--was that all American aviators should know the theories of flying and most of its mathematics. Concerning these things the French cared not a hang. Neither did the American aviators. But they toed the mark just the same, and many a youngster gnawed his pencil indoors and cursed the fate that had placed him with a country so finicky about air-currents on paper and so indifferent to the joys of learning by ear. The Americans accepted from the beginning the edict on squadron flying. It was as much a part of their training as field-manœuvres for the infantry. And because they had no golden days of derring-do to look back upon, they did less grumbling. Besides, there was always the chance of getting lost, and patrols offered some good opportunities to the venturesome. The air service had at this time an extra distinction. They were the only arm of America's service that had really impressed the Germans. The German experts, as they spoke through their newspapers, were contemptuous of the army and all its works. They maintained that it would be impossible for American transports to bring more than half a million men to France, if they tried forever, because the submarines would add to the inherent difficulties, and make "American participation" of less actual menace than that of Roumania. The Frankfurter Zeitung said: "There is no doubt that the Entente lay great stress on American assistance on this point (air warfare). Nor do we doubt that the technical resources of the enemy will achieve brilliant work in this branch. But all this has its limits ... in this field, superiority in numbers is by no means decisive. Quality and the men are what decide." Major Hoffe, of the German General Staff, wrote in the Weser Zeitung: "The only American help seriously to be reckoned with is aerial aid."