Derech Hashem – The Way of G-d 1:3:12
The soul enjoys a couple of other advantages in the Soul World which will ultimately benefit it and the body when they’re rejoined 1.
Since it was decreed that one could only achieve perfection after having experienced death, it follows then that even if someone actually earned it while he was alive (which is, in fact, the only environment in which one could earn it 2), he’ll have to wait for it.
What that implies is that the soul has to be exposed to sin and wrongfulness to one degree or another while the individual is in this world 3, and to become darkened and dimmed 4 as a result of that exposure. It also implies that the soul can’t express its full inherent luster while the individual is still alive 5, having been tinged that way.
Consequently, the body which could have benefitted and been purified from the soul’s luster can’t experience that in this world. And the soul suffers from the fact that it can’t manifest its luster in life too, since it can’t fulfill its raison d’être then, which is to purify the body, given that “things only achieve perfection when they fulfill their G-d-given purpose” 6. It’s clear then that both the soul and the body lose a lot in life.
Ramchal’s point, then, is that the soul attains some of what it lacked for in life while in The Soul World. It can radiate fully there, and its ability to purify the body is bolstered there, too 7.
1 In the text Ramchal makes two points about the soul at this point: that it “rests” in The Soul World — i.e., it remains in a state of suspended animation there; and that it also “looks for the body” there. That is, despite the spiritual advantages it will enjoy in The Soul World described below, at bottom the soul sits motionless awaiting its reunion with the body and wishes it could be with it in The Soul World, too. That comes to underscore the partnership and the love of body and soul rather than the sort of antagonism between them that others would posit.
2 “This world is like a vestibule before the World to Come; prepare yourself in the vestibule, so as to enter into the banquet hall” (Pirkei Avot 4:16); “‘You are to do (the mitzvahs) today, and not postpone them for tomorrow; since (while you can) do them today (in life), tomorrow (i.e., The World to Come, is set aside) for receiving the reward for (having done) them” (Eruvin 22a). Also see 1:3:3.
3 Which is so abhorrent and foreign to the soul.
4 I.e., demoted and demeaned.
5 I.e., it cannot be itself.
6 Along the same lines, Rambam contends that something is termed “good” only when it fulfills its life purpose (Moreh Nevuchim 3:13).
7 And it can thus “be more of itself” there. That is, like a bird that had been kept cooped up then set free, the soul’s release from the body enables it to fly, preen, and breathe freely. But the soul will not achieve its full capacity until The World to Come.
Rabbi Yaakov Feldman has translated and commented upon “The Gates of Repentance”, “The Path of the Just”, and “The Duties of the Heart” (Jason Aronson Publishers). His works are available in bookstores and in various locations on the Web.