In 'A Search For Spock', Sarek makes it perfectly clear that it is Vulcan custom for Kirk to have returned Spock's soul (or katra) that he mistakenly believed Kirk to have been given.

At the end of the movie, when the regenerated Spock is returned to Vulcan, it is stated that the ceremony (the 'fal tor pan?'), to rejoin the new Spock with his katra, has pretty much only ever been performed in legend.

What, by Vulcan custom, was to have been done with Spock's katra if the unlikely event of his regeneration hadn't taken place?

3 Answers 3


It is implied that most Vulcan's katra remains with whatever Vulcan receives it - it is treated as a part of their soul, given to others to be remembered by. A piece of them will be with their closest loved one (the intended recipient of the katra) for the rest of that Vulcan's life.

This is evidenced by the fact that what Spock regains is NOT complete - he has to relearn much. The seemingly full restoration he has by the end of his run most likely has more to do with his body being regenerated - the combination of his soul fragment and the restored brain (which would still retain his memories, given the regeneration on Genesis) did it.


In several of the novels, the soul is transferred to a stone, where it can be mind-touched.

Given some of the episodes in the Enterprise series, this approach seems to have been dropped in favor of the passing along theory.

So, either he would have...

  1. remained in McCoy, driving him insane
  2. been placed into a stone
  3. been transferred to someone who could handle it, almost assuredly a Vulcan.

It should be noted that as of Enterprise, it's a forbidden practice by an underground movement within vulcan society; by the time of the TOS-Crew Movies, that faction has come to power.

Fanon tends to use one or the other.

  • It's worth noting that, unlike Star Wars novels, Star Trek novels are not canon by default.
    – Jeff
    Sep 1, 2011 at 13:03

Personally, I think the term 'soul' is wrong here (though, depends on definition). As far as I understood those scenes, Spock transferred his knowledge, memories and pretty much what makes up his personality into the brain of McCoy. During the ceremony on Vulcan it was transferred back into the brain of Spock (it must be quite a feat to split two personalities and minds).

The problem was, McCoys brain was far too primitive to handle that kind (and amount) of information. That's why he slowly went nuts and that's most likely also the explanation why Spock had to relearn quite a few things. During the movie we can see that McCoy has problems differentiating between his mind and that of Spock. So I think that McCoy simply would have gone crazy with time, losing his and Spocks mind on the way down the rabbit hole.

Now that I think about it, it seems quite logical that Spock was 'less' human after the ceremony. The priestess needed to sort out what belonged to Spock and what belonged to the human host, not knowing that Spock had ...uuuhhhh... achieved quite some human traits, she simply assumed they belonged to McCoy.

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