Physics, my friend, is a narrow path drawn across a gulf that the human imagination cannot grasp. It is a set of answers to certain questions that we put to the world, and the world supplies the answers on the condition that we will not then ask it other questions, questions shouted out by common sense. And common sense? It is that which is understood by an intelligence using senses no different from those of a baboon. Such an intelligence wishes to know the world in terms that apply to its terrestrial, biological niche. But the world—outside that niche, that incubator of sapient apes—has properties that one cannot take in hand, see, sniff, gnaw, listen to, and in this way appropriate.