Orbis Tertius is a Latin phrase used by the philosopher Karl Popper to denote "the world of ideas in the objective sense," a third world that is different from both the physical world and the mental world. It consists of objects of thought: theories, arguments, and problems distinct from the thought processes that create them and the physical objects that inspire them. Humans make this third world, and yet it transcends its makers, as when bees produce honey or a spider spins a web. This world that is fundamentally human exceeds the human grasp, leaving room for change, discovery, and creative freedom. Because humans cannot completely comprehend or control this world of their making---because it has autonomy--it pushes us to grow, yet as we grow, we push its boundaries also, enlarging the world of ideas. For more detail, see Popper's essay "The Three Worlds"; also see the wonderful short story by Jorge Luis Borges, "Tlon, Uqbar, Orbis Tertius."