The fourth season of "Lost" is nearly halfway through its entire run (only 13 episodes overall), and this may be without question the finest collection of episodes so far. Every week has delivered: every week has deepened the mystery without being obnoxious and given the fans answers they have been grasping for. "The Constant" deals specifically with the idea of time travel and how it is a very present problem on the Island. This was an intensely detailed and convoluted episode, so hold tight people, and come on a journey with me.

Desmond, the Scottish seer, is traveling on the helicopter with Sayid and Frank. Last week, Jack and the Losties were worried because it had been an entire day with no word from them. While traveling straight through a sudden storm, they try to remain on the course Daniel set for them, but they steer just a little off ... with disastrous results. Desmond flashes back to his stint in the army in 1996, and then his conscious mind from 1996 comes back to 2004 with absolutely no recollection of where he was or who the people around him are. Desmond is terrified of this confusing situation, especially since he still flashes back and forth between the past and the present, and they land on the freighter just in time.

The freighter people are menacing and very unhappy that Sayid and Desmond have come back with Frank. They do not seem surprised to see Desmond going crazy either and bring him straight to the sickbay where he meets George, the man who used to speak to the Losties on the radio but has now lost his mind as well. Sayid insists on calling the beach where Daniel hears the situation and strangely becomes a much more assertive and knowledgeable source. He is the first person in the course of this show who so readily gives information to the Losties and in a concise, clear way. He knows exactly what is happening to Desmond and tells him to find his past self in Oxford. Desmond does so in 1996, with strict instructions on how to make Daniel believe him.

Daniel shows him -- and us -- a time travel machine with a rat, using the instructions that Desmond remembered. He explains that what Desmond needs is a "constant," something to ground him in both realities. The entire TV audience knew who that was going to be. Penny! In one of the most heartbreaking and beautiful scenes on "Lost," Penny and Desmond are briefly reunited over the phone, and it would take a cold heart indeed not to mist up at their passionate promise to find one another again.

A few side pieces to remember: they have a "friend" on the freighter who helped Sayid and Desmond get out of the sickbay. Is this Ben's spy, or someone else? Daniel explained that while almost two days passed on the Island, a much shorter time passed for the helicopter, and this brings into play whether or not the Island is outside of the regular passage of time and space. It has a great deal to do with electromagnetic energy, since that was the reason he believed Desmond got thrown through time. Also, Mr. Widmore makes an appearance buying an artifact journal from the Black Rock that was Captained by Magnus Hanso. If that didn't ring any warning bells for loyal fans, I would be very disappointed in them.

Daniel Faraday quickly rose to be an esteemed member of this cast, and he is probably one of the few characters to know what is going on and be willing to share his information. This is probably only the start of an exploration into time travel and the strange abilities of the Island and probably the reason Daniel is there at all. Tell us more, Professor Faraday!

Desmond and Penny are an anomaly; what should be a very cliche and overdone romance has instead become the most touching and believable couple on "Lost" -- possibly on television. This is a couple who broke up nine years ago and has only spoken a handful of times in that long separation, but they still are irrevocably tied. Their devotion, belief, and pure love for one another is the kind that storybooks dream of, and it resonates in the hopeful hearts of people everywhere.

Coming up next week is an episode titled "The Other Woman," an amusing play on the fact that Juliet is the other woman in Jack's life, and also a female Other. It will be her episode, and this hopefully promises some more insight into the Other world.

Recap by Chelsea 'Dee' Doyle
Starpulse contributing writer