photons produced in the sun scatter through the atmosphere until the strike the surface on which text is imaged. these photons are then either absorbed (by black ink) or scattered back towards my eyes (for anything that's not black). the scattered photons, if they reach my eyes and pass through the iris, will strike the retina, producing a nervous response. the optic nerve, in conjunction with my brain, will convert these signals into qualia (or some similar concept) of words.