" Question: what weighs five quadrillion tons but you cannot see hide nor hair nor hint of it? Answers: Guilt, responsibility, fatherhood, sorrow, love, history—but here I mean that most crucial of freighted invisibilities, air, the atmosphere, our atmosphere, the incredible blanket we breathe, without which our sphere is only another among zillions of lifeless rocks let loose in the endless void. Five quadrillion tons! The parade of zeroes like a circus train behind the engine of the five: 5,000,000,000,000,000 … "

― Brian Doyle , Children and Other Wild Animals