You’re not precisely in a sealed bubble. You’re in a 3d Venn diagram like scenario with towers, some overlapping, but you can still see something of the non overlapping ones. This is how you can know something about a thing that you’re not in. You’re never wholly in the dark.
Related concepts include prisms and triangulation. Prisms locate direction by tracing unity to diversity and diversity to unity. Triangulation locates position by combining meaninglessness into meaning.
