Chronology, was defended by Flandry, the Galactic Archaeological Society clearly exists at a much later date.
SM Stirling's The Scourge Of God is set in Change Years 23-24 but quotes a song that is attributed to a figure in the 1st century CY. This attribution thus implies a later perspective although we are not told anything about that later period.
James Blish's The Quincunx Of Time reverses this familiar historical process because its protagonists in our future receive messages from various periods of their future. HG Wells' The Time Machine can have no later perspective because the Time Traveller witnesses the end of life on Earth.
It is always illuminating to compare Anderson, Stirling, Blish and Wells.