Iterative knowledge
The purpose of science is to get closer to truth. There is always things we don't know, or can't prove. The things we need to believe in, as scientific theories. The truths, until proven wrong.
Long time ago we believed we were living at the center of the universe. Later we have found out we are actually living at a rather unassuming edge of an average galaxy somewhere around the universe. We don't even live at the centre of our own solar system. Throughout the history we have iterated our place in the universe.