Source: pp 114-115, Think: A Compelling Introduction to Philosophy (1 ed, 1999) by Simon Blackburn. See page 15 of 18. Please advise if I should reproduce two pictures omitted below (which I omitted to minimise post length).
But suppose you don't know what is going to happen, but it is known, perhaps to God. Or just: it is knowable. We think, as we deliberate, that the future is open, but the past fixed. But suppose the future is as fixed as the past is. Thus we think like this: [Picture omitted.]
-- where the arrows represent open possibilities, spreading out from now.
[1.] But perhaps this way of thinking is illusory. Perhaps the truth is only seen from a "God's eye view", or what has been called the "view from nowhen". From this perspective, time is laid out like a celluloid movie film; a frame of the film corresponds to the events at any one time. Given the way the world works, we can be aware only of past frames (sometimes people think that prophets can 'see' future frames). But there is no metaphysical asymmetry between past and future: [Picture omitted.]
If that's the truth, we might think, surely it is as useless trying to influence the future as it would be to try to influence the past. If God has this view, he must be looking at our efforts, and laughing.
Please explain the bolded: What is metaphysical about asymmetry?
From reading these few paragraphs (from The Big Questions: Philosophy, by Simon Blackburn), here is my conjecture of the meaning of : Only God can accesses the 'view from nowhen', which resembles a movie film that can be unrolled infinitely and that already depicts our past and future as already having been decided. In contrast, humans see only the past and not the future.