Although Blavatsky did not have a great deal to say on the individual soul after death, she was extremely critical of the views of her rivals the Spiritualists.
Blavatsky thesis against Spiritualism is as follows: the so called "spirit" of the departed that the Spiritualists claimed to contact through seances and mediumism are not so much deceased souls as lower personality remnants. Blavatsky refers to this remnant as the "Elementary" or "Spook" (or what some later theosophists and occultists call the "Shell"). As she explains:
"The animal elements or power of desire..., absorbing after death that which it has collected (through its insatiable desire to live) during life; i.e. all the astral vitality as well as all the impressions of its material acts and thoughts...forms the "Spook" or Kama rupa....(A)fter death the higher Manas unites with the Monad [Spiritual essence] and passes into Devachan, while the dregs of the lower manas or animal mind go to form this Spook. This has life in it, but hardly any consciousness, except as it were by proxy, when it is drawn into the currents of a medium."
Blavatsky's understanding of the disincarnate personality as a mere shell or shadow of its former living self is actually derived from the old Greek idea of the eidolon, the pathetic shade which remains after death. Blavatsky herself was very well-read, and thus quite familiar with this old Hellenic theme. But she gave it a new twist by applying it as an explanation for spiritualist phenomenon. The Spiritualist does not tune in to the whole human being, the disincarnate soul, but only fragment, a lower personality remnant.
If there is any truth in this thesis, it would seem then that the whole question of Spiritualism and spiritualist communications is not as simple as it seems. For in some cases it may involve actual channeling-type phenomenon.