I don't know any straight line in nature too. But what I see and heard also is that everything is rounded. Look at your body and under a microscope and at our globe and in the universe. Maybe everything consists of spheres? Researching smaller and smaller spheres, cells and atoms etc., scientists come to a border-point where there can't describe any matter any more, then they have to tell us there is spirit. Spirit rules matter. Well, we can think of this ourselves, our spirit rules our everywhere rounded body.