“One Breath” vividly diagrams the boundaries separating life from death, as well as Dana Scully’s “near death experience” at the shore-line between those states of existence.

Gratifyingly, the episode provides resonant visuals to embody this strange “border land.” Indeed, many of the episode’s images -- from the opening scene involving Scully’s childhood, to her journey to a long, white tunnel of memory -- prove unforgettable.

This episode from early in The X-Files’ second season also continues to chart Mulder’s emotional and moral disintegration, a painful path initiated fully in last week’s episode, “3.” Again, just to put in a plug for that commonly (and unfairly) maligned episode, “One Breath” wouldn’t work half-as-well if not preceded by “3,” a story which showcases Mulder’s guilt and consequent descent into nihilism.

As the final piece of the Scully abduction arc, “One Breath” also finds causes for hope and positivity. While Mulder keeps “willingly walking deeper into darkness,” Melissa (Melinda McGraw) -- Scully’s sister -- reminds him that there is nothing unnatural about death. She also notes that there is nothing silly or trite about holding onto belief.

And “belief,” of course, is a key theme of this imaginative and heartfelt TV series.

We see the theme given voice in Mulder’s near-constant refrain of “I want to believe,” and also in Scully’s strong religious conviction or faith, which would seem, on a superficial level, to clash with her obsessive focus on science.

But the important thing The X-Files seems to state is not what one believes in, but the fact that belief exists at all.

Accordingly, “One Breath” involves faith and belief (or lack of it) in virtually all the primary characters. Skinner delivers a stirring monologue here about his experiences in the Vietnam War, and the Cigarette-Smoking Man and X provide examples to Mulder of what he could conceivably become if he treads down the path of darkness: a lonely, empty, cynical shell of a man hated by all, driven only by the exigencies of his personal and professional crusade.

Without explanation, Scully (Gillian Anderson) appears in a local hospital, barely alive, in a coma, and showing signs of “branched DNA,” which suggests genetic experimentation. Her immune system “decimated” by this waste product, Scully clings to life.

A furious Mulder (David Duchovny), together with the Lone Gunmen (Bruce Harwood, Dean Haglund and Tom Braidwood) attempt to determine the cause of Scully’s condition, as well as a possible cure, while a mysterious care-giver, Nurse Owens (Nicola Cavendish) tends to Dana’s spirit.

A shadowy agent of the Cigarette-Smoking Man or “Cancer Man” (William B. Davis) attempts to steal a vial of Scully’s blood for examination, but Mulder is unable to interrogate the man because he is intercepted by his new government informant, X (Steven Williams).

Despondent over Scully’s condition, and by the fact that the plug will soon be pulled in accordance with Dana’s living will, Mulder goes after the Cigarette Smoking Man with the help of an unexpected ally: Assistant Director Skiner (Mitch Pileggi).

Death is the great unknown of the human condition. Because it is perceived as the “end” point of our journey on this mortal coil, it is difficult to examine dispassionately, or to fully understand. No one has come back and reported on the afterlife or lack thereof…at least no one credible.

So we who still dwell here must wonder: Are the phantasms of the “near death experience” a legitimate sign of another world beyond this one, or merely the brain’s chemical way of preparing and soothing us for that final moment of cessation?

“One Breath” finds a dynamic image to pinpoint Scully’s entrapment between worlds in this episode. She holds onto life, but death beckons. Accordingly, the episode depicts her sitting alone in a row-boat that is tethered to a nearby deck by a taut, stretched rope. Underneath the boat, the water gently laps, ready to push her towards another shore, one more distant and unseen. And when Scully is taken off of life-support in the hospital, this image recurs. But here, the rope snaps, sending Scully towards that distant shore…and away from us.

More than anything, these visuals suggest “the in-between” aspect of Scully’s condition. She could still travel safely to the dock (where we see Mulder, Mrs. Scully and the mysterious Nurse Owens waiting), or instead set a course for the unseen shore: towards death itself.

Another powerful scene in “One Breath” finds Scully ensconced in a kind of endless tunnel or corridor, visited by her dead father while she lays prone – in a white dress -- upon an antique table. Her father’s speech to Scully here is extremely moving (especially if you are a parent…). He emotionally speaks of all his life seeming like “one breath” or “one heart beat” because he is terrified at the notion of not seeing his child again. He would give up all his medals and honors, he says, to be with Scully again.

Many near death experiences are of this nature, and again, one can state that The X-Files is true to the literature on paranormal subjects. Those who have “seen “the light at the end of the tunnel” have also reported rejoining with lost loved ones.

Finally, “One Breath’s” kicker is that Nurse Owens is not a typical nurse at all, but a kind of “guardian” figure looking over Scully, protecting her. What I appreciate about the Nurse Owens subplot is that it can be -- in the spirit of many great X-Files mysteries -- explained in two ways. Either Nurse Owens’ is the voice of “survival” in Scully’s own mind, telling her to stay, fight, and hold onto life. Or she is something else…something, paranormal, like an angel or spirit.

The episode largely avoids Touched by An Angel schmaltz by not delving too far or deeply into Nurse Owen’s nature, and allowing her mystery s to remain just that, a mystery.

Given the episode’s visual exploration of Scully’s entrapment in that in-between Netherworld, it’s delightful to report that, in many ways, this episode is also a terrific one for the character of Mulder.

Here, Mulder sees two people who have taken the path of darkness: X and The Cigarette Smoking Man. They have become so paranoid, so locked in their “visions” of conspiracy and hatred that they have lost sight of their humanity and connection to humanity. X even states in this episode (to Mulder): “I used to be you.”

That’s the point.

If Mulder becomes the “player” that The Cigarette Smoking Man desires to see him as, he will lose all the love, happiness and connection in his life. Accordingly, the episode provides Mulder a dramatic choice concerning his future. He can remain in his apartment to surprise (and then murder…) the men who harmed Scully, or he can go to Scully in the hospital and make his peace with her life…and her death.

Rather than vengeance, Mulder chooses the latter course, and thus maintains his connection to the world, the very thing that differentiates him from the determined and black-hearted men of the conspiracy.

“One Breath” elegantly makes all its dramatis personae reflections of Mulder’s existential crisis. Skinner believed in something (patriotism, specifically) but then lost that belief in Vietnam. He nonetheless found the power and the strength to go on living.

The Cigarette Smoking Man is a shell of a human being, by contrast, sitting alone in a hotel room watching television without a friend or “connection” in sight. When Melissa warns Mulder that he could yet walk deeper into the darkness, this is no doubt the kind of life she envisions for him. It is a life without trust, light, or love.

One reason for my perpetual admiration of The X-Files involves its unswerving ability to meaningfully connect form and content. In keeping with that tradition, the visuals here prove nothing less than poetic, and successfully reinforce the idea that life is a mystery, sometimes terrifying, and sometimes profoundly inspiring.

In particular, I love the moment in “One Breath” when the world returns around Scully.

Notice how I describe that moment.

Scully doesn’t return to the world so much as it returns to her, taking shape and form all around her prone, coming-to-consciousness form.

In a sense, this image captures perfectly the essence of the human experience. We cannot see and experience the world -- or our death -- except through our own eyes.

And since how Scully and Mulder each “see” the world is a key component of The X-Files formula, this shot from Scully’s perspective is a powerful reminder that -- after weeks of chaos and pain -- order is restored.

Both of our lenses – belief and science -- are back. The journey continues.

Next week: another X-Files classic (and a real creep-show…) “Irresistible.”