Revelation is supposed to be an apocalypse,” an unveiling. If so, why is it so obscure at so many places?

Good question, and we get a partial answer by following the flow of the book as a whole. Once we get past chapter 17, with its obscure references to kings and mountains and horns and kings, the book becomes remarkably straightforward. Babylon falls in cheaper 18 and different groups lament. Nothing obscure there. Then there’s worship and warfare, and another city comes from heaven. The millennium is controversial, but it’s not a puzzle on the same level as 666. In the final chapters, John clears up every obscurity with a this-is-that interpretation. Foundation stones are apostles, gates are tribe, the river is full of the water of life etc.

The overall effect of the book is one of increasing clarity, and the reader has precisely the experience of unveiling. When e Bride descends, everything suddenly becomes transparent as the gold of the city itself.