The book can only tell you from its own reference frame. Time has passed since the book was published, a lot of relevant opinions have come out in the meantime.

The book can only tell you from its own reference frame. Time has passed since the book was published, a lot of relevant opinions have come out in the meantime. A publication also somewhat assumes what the reader knows, because it would take forever to explain things otherwise. With time passing, those assumptions are no longer valid.