“It is a strange, nonintuitive fact of our existence that photons of light have no color, sound waves no sound, and molecules no odor. While we have the overwhelming impression that the greenness of the trees and the blueness of the sky are streaming through our eyes as through an open window the waves of light impacting on the retina are colorless, just as the waves of sound impacting on the eardrum are silent, and scent molecules have no smell. Our brain only receives input as electrical impulses and it creates the world we experience, inside our heads.”
— Bill Bryson, The Body