" He hadn't encountered a single soul on his run. This wasn't a popular part of the wood. You could probably die here and not be found for weeks. If ever. The same was true for a tree, he supposed. If a tree fell in the forest and there was no one to hear it, did it make a sound? Although it sounded like a Zen koan (yes, he knew the word "koan"), really it was a scientific question, to do with vibration and air pressure and the physiology of the ear. If a man fell in the forest--?
He went flying, tripping on a tree root that had been waiting in hiding to ambush him and exact revenge for his ignorance. More punishment for his knees. At least there was no one around to see his pratfall, although if he listened carefully Jackson thought he could hear the sound of one hand clapping. "

― Kate Atkinson , Big Sky (Jackson Brodie, #5)