The overriding arc in The Americans is that the pictures feel as if they were made by a feeling, thinking human, rather than someone trying to make photographs that look like art for the Christie’s auction. There’s a quick mind behind the book’s main equation, which is this: how we see is less important than what is seen. The former are questions for a machine: which lens? Which film? Which speed? The latter includes the most severe and gut-wrenching choices for a dedicated, free-thinking artist.