No history can be expected to furnish a full record of all the acts of prowess that were performed in the air during the long course of the war. Many of the best of them can never be known; the Victoria Cross has surely been earned, over and over again, by pilots and observers who went east, and lie in unvisited graves. The public dearly loves a hero; but the men who have been both heroic and lucky must share their honours, as they are the first to insist, with others whose courage was not less, though their luck failed them. There is a quaint system, in use in the air service, of reckoning the activities of the service in terms of hours flown, taking as the unit for addition every single hour flown by each individual machine. By this method of calculation, the hours flown by the air service, on all fronts, during the war can be shown to be much over a million. The work of an ant-hill, reckoned on the same basis, would present a stupendous total. If the heroism of the air service, that is to say, their deeds of surpassing courage and devotion, could be thus computed, the figure would run into thousands; and this would be the fairest, though not the most dramatic, statement of the case. The officers in command have always been unwilling to pay regard to 'star turns'; what they have coveted for the service is not a low range of achievement rising now and again into sharp fantastic peaks, but a high tableland of duty and efficiency. They obtained their desire, in a result more surprising than any single exploit can ever be. They made courage and devotion the rule, not the exception. The work of the air service on a war front consists of often-repeated short periods of intense strain. One pilot described it well by saying that it is like going to the dentist every day. To exact the highest standard of conduct under this strain, not as an ideal to be aimed at, but as a working rule, might well seem to be winding up human nature to a point where it must break. The commanders of the air service did not hesitate to take the risk. They trusted human nature, and were amply rewarded. The experiences of the war revealed, to a generation that had almost forgotten them, the ancient and majestic powers of man, the power of his mind over his body, the power of his duty over his mind. When the builders have been praised for their faith and for their skill, the last word of wonder and reverence must be kept for the splendid grain of the stuff that was given them to use in the architecture of their success.