Or sit in a dark room, unable to see anything. There is more to it. See, e.g., <a href="https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Emission_theory_(vision)" rel="nofollow">https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Emission_theory_(vision)</a>