“The future is there," Cayce hears herself say, "looking back at us. Trying to make sense of the fiction we will have become. And from where they are, the past behind us will look nothing at all like the past we imagine behind us now.”

Source: A Living Nightmare

1990

Variant: A very wise man once told me that you can't look back-you just have to put the past behind you, and find something better in your future.
Source: Salem Falls

Words of Wisdom from Buddhist Master Jun Hong Lu, Volume 1 (2016) ISBN 978-0-6482300-1-4

Exploration of Space (1952)
1950s
Context: We stand now at the turning point between two eras. Behind us is a past to which we can never return … The coming of the rocket brought to an end a million years of isolation … the childhood of our race was over and history as we know it began.

David Trimble in: Peace 1996-2000 http://books.google.com/books?id=zCmliED4M_UC&pg=PA114, World Scientific, 2005, p. 114

Source: Barbarian Sentiments - How The American Century Ends (1989), Chapter 1, Dead Stars, p. 3.

Short story, 'Aquifer' - p.53
Short stories, The Turning (2004)