"The Old Age of Nostalgia" - Mark Strand,

Those hours given over to basking in the glow of an imagined
future, of being carried away in streams of promise by a love or
a passion so strong that one felt altered forever and convinced
that even the smallest particle of the surrounding world was
charged with purpose of impossible grandeur; ah, yes, and
one would look up into the trees and be thrilled by the wind-
loosened river of pale, gold foliage cascading down and by the
high, melodious singing of countless birds; those moments, so
many and so long ago, still come back, but briefly, like fireflies
in the perfumed heat of summer night.