Whenever calamity howlers shake their heads and impress upon...

Whenever calamity howlers shake their heads and impress upon you that this, that, and the next dire catastrophe is to befall this nation or the nations of the world-such as, for example, that exhaustion of the world's oil supply will bring all transportation and machinery to a standstill through lack of lubrication, or that exhaustion of the earth's stores of coal will make life unlivable in these cold climates-just smile and reply that the worst troubles of all are those that never happen [and] that you prefer not to cross shaky bridges until you come to them....