From the beginning of the initial civilization, human beings transformed sound into a symbol, tied ropes and recorded events, thus crossing the long river of history. History has changed mankind. Words will remember all memories. First-class civilization is a very long span table, because mankind will shine with words. When a first-class civilization enters a second-class civilization, PI represents a latitude, an ability called God. However, gods do not exist. Latitude is a kind of cognition in a broad sense. Since then, mankind has stepped into the era of interstellar navigation. But for the three-level civilization, the so-called interstellar navigation is more like a fish in a pond. It is impossible to get rid of it and more difficult to spy on it!