Interesting thread.  I think Mark is right (that nostalgia is
reactionary), Chris is right (that it's inevitable), and Rebecca is
right (that poets resort to it for contrast and perspective).  Borges:
"Misery requires lost paradises."  (It's odd that for years I misquoted
the first term as "happiness.") I myself miss the Sixties - thought I
wasn't uncritical while they were happening and am not now.  Four years
ago they inspired my one overt pastoral, which might amuse you:


For Flute


With word that the poet has married,
a cloud comes over the park.
Aelita puts her blouse back on,
her motion as slow
as that of the frisbee
directly above her, affected by a convention
that has leaked into Arcadia
from Media, and which no longer 
reveals anything.
Of course she's upset:
she has just returned from a workshop
in the hot and verdant 
valleys upstate, her mind lucid,
pleasurably empty, and now
(though the time of the fact
as opposed to that of its discovery
is, as always, unclear) - now this.

They are all upset - Aelita, Cynara,
Woodbine.  But the consequences
of acting out
float, in the form of historical examples,
in the air above the grass 
like oppressive hallucinations.  So Aelita 
strives for detachment, and Woodbine
outlines a work of art;
and Cynara
begins to construct a remark
that will later seem spontaneous
and displace expected feelings - something 
hopefully less annoying
than the Et In Arcadia Ego
carved everywhere on stones 
that are just out of sight of each other.  Such at least 
is her purpose.

They win the battle over themselves
and gaze at one another.
Blonde down.
Javelin tightness.
The curve from armpit to breast, a suggestion of moisture
on … And what they are wearing
so pleases (first and foremost) them,
while so sweetly blending
the classical and disposable, that I couldn't describe it.
Meanwhile the boys
now entering that part of the park
with dogs and thoughts
(which become pretexts) are similarly wise:
they pretend they can interest,
initiate, stimulate, 
but they have merely been summoned,
and accept that.

But how is it that these kids
can talk to each other
without edgy pretension,
giggly airheadedness, or irony?  
(or the sanctimoniousness
I imagine instead?)  Or that the music
filling the tidy grove -
the sun comes out and tops come off 
again - is subtle and optional,
though here too the technology exists
to replace consciousness?  
They seem polite, these kids,
almost like Canadians,
and despite the warmth
it is as if
a Canadian chill had settled,
reducing numbers while increasing dignity.

Aelita describes the tall grasses
and wild grazing herds
on the way to her workshop.  Colin 
recalls a retreat
in a northern forest, trackless and damp 
and spreading.  Woodbine picks up on
the spiritual theme; 
her statement invokes 
scientific knowledge.  And Che,
the one with good weed, 
tells of a desert
where his job was to search for someone
to help.  He says that immortality
in no way implies a circle,
but the retracing, 
not perceived as such,
of a given line.

And as day wanes, they go home. -
In my lonely early youth I asked
a friend's older sister
what made her decide to sleep with someone.
Was bracing myself 
for some D. H. Lawrence deluge when,  
surprised, she said, "Oh, I'm lonely or cold,
or I'm enjoying talking - "  
and for the first time
it seemed possible.  Something similar
occurs here, 
abetted by vast 
empty neighborhoods where
the grass and trees and predators return
or never left.  During the day
one tends these.  
At night one pairs off. 

Then, very late, Aelita or Cynara,
lit by a candle,
looks out a window
and, thinking of the poet, sighs
and wishes him the best.
The room behind her, whether hers or Colin's
etc., would be much the same
in any world.
The books are the same, in their slow changes.
The posters would be different,
presumably, if what they stood for 
were ever victorious.  
Or perhaps not.  Those images of struggle
flicker forever beside
joyful swirls of synaesthesia,
boddhisatvas with closed eyes and smiles,
and that other, blue-bodied god among his milkmaids.