"We shall not cease from exploration / And the end of all our exploring / Will be to arrive where we started / And know the place for the first time." - T.S. Eliot

Tonight's milestone episode of NCIS showed viewers a side of Leroy Jehtro Gibbs we've never seen before, which was the point, as the bulk of the action did not actually take place, other than in his mind.

I have not seen the 1998 film Sliding Doors, upon which "Life Before His Eyes" is loosely based, but I'm intrigued after Gibbs' introspective journey proved to be funny, moving, and surprisingly complex.

Only by looking back at the decisions he's made and the wide-ranging ripple effects that followed could our fearless leader truly understand the scope of what he's accomplished over the decades.

Seeing his life, in a sense, again for the first time.

Gibbs would love to live in a perfect world, to have it both ways. Wouldn't we all. But it doesn't work that way, as he learned time and again. That said, Gibbs wouldn't have his world any other way.

The filming style and the presence of familiar faces, past and present, going about their business in the diner gave the episode a surreal aura, one which could have fallen flat had it not fulfilled a grander purpose.

Leave it to old, wise Mike Franks (Muse Watson) to talk the original Probie through this out-of-body experience, one that reintroduced memorable characters and rehashed monumental NCIS events.

Mike's "Swan Song" last spring was another unconventionally brilliant installment, so it was only appropriate that Gibbs' longtime friend and mentor played something of an otherworldly role this time around.

With the help of Mike and others, Jethro came to the realization that everything that's happened and every choice he's made - even those with tragic results - has brought him to where he is now.

A simple message, but nonetheless profound. It doesn't work that way. We heard those words often as Gibbs relived not saving Kate, Kelly and Shannon, only to consider what good resulted from such devastation:

The team coming together. The criminals and terrorists locked away. The families given closure after suffering unspeakable losses. Gibbs' own family being spared that inevitable, dreaded knock on the door.

His choice. His life.

Utopian, it's not, and there will always be mistakes and what-ifs. But for a man who gets up every day with the purpose of protecting and serving others, it's hard for Gibbs to have many regrets in the end.

The alternate-reality scenes were near-perfect, offering terrific "here's to the fans" moments while dovetailing with the broader narrative and without dragging on so long as to feel like contrived, cheesy filler.

That's a tough line to walk and while some fans may have wished for a boilerplate episode - I was more than a little skeptical of the concept headed into the hour - it was executed flawlessly.

There were clear parallels between the case of the week, involving a father who did what he thought was just, despite the moral gray area he clearly crossed, and Gibbs' own contemplation.

Without that case and how Gibbs' lessons at the diner applied to it, this story would not have resonated, but Gary Glasberg's teleplay and Tony Wharmby's direction struck the right balance.

Gibbs' rendezvous with Shannon and Kelly was the night's emotional high point, as well as his personal turning point. His loss would instead have been their loss, and NCIS would never have known Gibbs.

It felt like 2005 again with a flashback to Kate's demise, only to give way to a glimpse of what might have been. Think she really would have gone on to marry and have a child with DiNozzo?

Interestingly, in the other alternate universe, where Tony did not appear, Kate's baby was of the opposite gender, likely alluding to the fact that Tony wasn't in the picture in that scenario.

Seeing a married Tony wasn't just a gimmick, either, as we've witnessed him yearning for more out of life this season, and are about to meet the woman he was once engaged to marry, Wendy.

McGee-Abby fans were no doubt loving that couple's role, too, but unlike Kate, they're still around and very much fond of one another in reality. Might this be a gateway to something more?

Fortunately, he's not taking the job on Okinawa. What did Tim mean when he said he had more to accomplish here? He didn't have time to elaborate, but he couldn't mean just professionally.

"Life Before His Eyes" was not only an NCIS benchmark, but a crossroads for the characters that made these 200 episodes so strong; A reflection on where they've been, where they might've gone, and where they're headed.

For Gibbs, he's finally let go of the guilt. For the rest, we'll have to wait and see.

The screen faded to black with a thank you to the fans who've made this the #1 drama on TV in recent years. With episodes like this, the fans owe the actors, writers, producers and crew thanks as well.

A few closing thoughts and observations - and please, add your own below, because there are almost too many to list after such a head-spinning hour - before turning it over to your comments:

• I loved seeing Gibbs' father (Ralph Waite) as well as young Gibbs (Sean Harmon) and Matteson, from this season's "Engaged", even if they were mostly on the periphery.
• It goes without saying, but Mark Harmon was outstanding tonight.
• Gibbs' mom was a redhead, too? Somehow not surprising.
• Did Sasha Alexander actually film that scene, uncredited?
• Tony calling faux Ziva "Tiva" in the interrogation? Classic.
• Who knew Palmer had abs like that, indeed.
• ROLFING?
  

What did you think of tonight's NCIS? Discuss below!

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.