When you try to remember where you saw an item of information, you probably refer to the URL or the link that drove you there, but you don't have much more to help you. And the light is also very important. In the electronic media the screen is retro-illuminated. Marshall McLuhan guessed that this characteristic would induce a mystic reverence in the spectator, as the stained glass windows in the churches did during the Middle Ages. Moreover video light shines on the retina stimulating the sight considerably. Paper, on the other hand, is front-illuminated, which is much more relaxing for the sight, and its light changes according to the environment.(Alessandro Ludovico)