I have decoded Codex Argenteus from Uppsala University Library by using the Peruvian ethnographer Daniel Ruzzo`s principle of solar light tangency and watcher`s position. The principle, intuited previously by the author of Prehistoric Dacia, Nicolae Densushianu, by photographing the Bucegi Mountain Sphinx, and developed by the historian Ion Gheorghe, can be applied to Uppsala Codex folios in the summer days, after 6 PM, just like it can be applied to Stonehenge Megaliths which were inscribed with megalithic ideograms that react to Ruzzo`s Principle, and to Celtic Coins. The discoveries have a wide field of application, starting from computational linguistics, quantum light model, to the developing of new energetic techniques or new light communication ways.