What would you call America's most priceless asset? Surely not its limitless natural resources, not its matchless national wealth, not its unequalled store of gold, not its giant factories, not its surpassing railroads, not its unprecedented volume of cheap power. Is not its most priceless asset the character of its people, their indomitable self-confidence, their transcendent vision, their sleepless initiative and, perhaps above all, their inherent, irrepressible optimism?