The essence of the 1. Godel theorem can be reduced to the fact that one can always find a self-referring sentence. It is intuitively clear that such sentences lead to problems, which, indeed, is the source of the Godel theorem. Can someone explain to me why it is not possible to construct a relatively general logical system that does NOT contain self-referring sentences? I would appreciate an intuitive, rather than a rigorous explanation, as I am not a mathematician (but a theorethycal physicist). If that question has already been answered, please provide me a link.