"The Leap Home"
	The two "Leap Home" episodes are arguably the best in the
series -- and I say that as someone whose favorite will always be
"M.I.A."  They are thematically textured on many levels, almost
flawlessly executed, and (not to underestimate the importance of
this) wonderful and well-paced stories, the kind that would be
ruined if they went on any longer, but which you nonetheless wish
could go on forever.
	Thematically, "M.I.A.," "The Leap Home," and "The Leap Home:
Vietnam" form a compelling trilogy (actually more internally
consistent than the fifth season episodes which bore that name)
about love and longing, desire and deceit, loyalty and limits. 
They are partly about what it means to be a Leaper, and are
certainly concerned with the ethics of time travel.  But they are
also about what it means to be human -- evoking, as Orson Scott
Card said in his Introduction to Maps in the Mirror, "the
ultimate mythic response: 'Yes, that's how people are.'"
	I've already talked about the concept of Limits in my comments
on "M.I.A."  Part one of "The Leap Home" reprises this theme, this
time reversing Al's role with Sam's.  Where Al was trying to use
the power of time travel to repair his doomed marriage, Sam tries
to use it to change the fate of his father (who died too early,
from Sam's point of view), his sister (who eloped with an abusive
drunk), and his brother (who died in Vietnam), when he has actually
Leaped into himself at sixteen to win a basketball game.  The
similiarity is easy to see; the difference is more subtle: in
"M.I.A.," Al was trying to work through Sam, and Sam, who had no
personal connection to Al's marriage, was able to keep a level head
and recognize the Limit as soon as it became clear.  In "The Leap
Home," Sam has the initiative, and Al does not have the power to
stop him -- all he can do is counsel, and hope it sinks in.  In
what is perhaps the best scene in the trilogy ("perhaps" because
very little can compare with Al's farewell to Beth in "M.I.A."),
Sam realizes that the Limit is not artificially imposed, that he
isn't changing anything, that he _can't_ change anything, and runs
out into his father's cornfield.  He shouts to the sky that he is
going to quit, that it's not fair.  Al tells him, "I think it's
_damn_ fair."  Finally, Sam realizes that he has been given a great
gift in the ability to actually be with his family again, and lets
go of his hubristic (and fruitless) attempt to dictate their
fates... except for one fate: his brother Tom's.
	In part one, Sam makes a deal with Tom: on April 8, the day
Tom is supposed to die, he is to "crawl into the deepest, darkest
hole in Vietnam."  Just before Sam Leaps out, Al tells him that the
deal didn't work, and Sam shouts "Tom!" then finds himself wading
through a low river in Vietnam with Tom's SEAL squad -- and under
fire from snipers -- and the final segment of the trilogy begins.
	Sam is, of course, not there to save Tom; according to Ziggy,
it is likely that he is there to save the life of Colonel Deke
Grimwold, who will be killed in a sniper attack on April 7.  Al
reminds Sam that it is possible that he will Leap immediately after
the attack (and therefore be unable to save Tom), but Sam warns
Grimwold anyway.  The sniper attack, mysteriously, does not occur,
and Sam doesn't Leap out.  Why?  Sam is convinced that it is so he
can save his brother; Al insists that it is to make the mission
they are going out on, called Operation Lazarus, a success.  We are
not immediately told what the mission entails -- Al stays to listen
to Grimwold brief Tom about it, but we follow Sam out of the tent. 
We later learn that Al is again trying to change his own life; he
is one of the POWs that Tom's team is being sent in to rescue.  
	In "M.I.A." Al was never forced to accept that he couldn't
change his life -- Sam simply wouldn't do it -- but in "Vietnam,"
he has to make a conscious choice between sending Sam after the
POWs who are being pulled down a nearby trail or helping him get
back to the SEAL squad to warn them that there is a traitor among
them, and they are walking into an ambush.  He chooses the latter,
and Sam is able to save Tom.  Had Sam known at the time that Al was
one of the POWs, it is likely that he would have frozen up (exactly
what his partner, Roger Skaggs, from "M.I.A." warned him about),
and the mission would have failed _and_ the squad would have been
lost, but Al doesn't tell him until later that night, when a pile
of photos taken by journalist Maggie Dawson reveals his face as he
was dragged down the path.  When Sam recognizes him, he looks up
and says, "You could've been free."  Al smiles sadly and taps his
head.  "I was free," he says.  "Up here, I was always free." 
This is a statement with many levels -- on the surface, it is
exactly what it is: Al redefining what freedom means.  A level
beneath, he is trying to reassure Sam that it was okay to save Tom. 
And then, on its deepest level, it is a statement that Al has
accepted that he cannot change that part of his life -- perhaps
even suggesting that he would have been less free if he had
convinced Sam to go forward, though that might be stretching it.
	Was it morally fair for Sam to save Tom?  The question is left
open.  It wasn't blocked by a Higher Power of any kind, but Sam had
to trade (as he put it) "a life for a life."  Without really
thinking of the consequences, just hoping for a story Ziggy could
access on the mission, Sam had convinced Tom to let Maggie Dawson
accompany them.  Not only did she never file a story, she was
killed when she stepped on a land mine while running back to the
chopper... possibly dying in Tom Beckett's place.  She was awarded
the Pulitzer for her last photo -- of Al -- but that is cold
comfort, and there was no reason she had to die for it only yards
away from freedom.  Was it worthwhile?  We're never told.  We don't
know what Maggie would have done with her life, or what Tom
actually did.  Perhaps it worked out as it should have.
	But we don't know.
	And that is the perfect ending to this bittersweet trilogy.