A philosophical concept expounded in The Road to Immortality (1932), a script purporting to be from the deceased and discarnate F. W. H. Myers as channeled through British medium Geraldine Cummins. The concept posits a number of souls bound together by one spirit, acting and reacting upon one another in the ascending scale of psychic evolution. There may be contained within that spirit any number of souls, according to Cummins:
"It is different for each man. But what the Buddhists would call the karma I had brought with me from a previous life is, very frequently, not that of my life, but of the life of a soul that preceded me by many years on earth and left for me the pattern which made my life. I, too, wove a pattern for another of my group during my earthly career…. I shall not live again on earth, but a new soul, one who will join our group, will shortly enter into the pattern or karma I have woven for him on earth…. Here, in the After-death, we become more and more aware of this group-soul as we make progress. Eventually brethren … its spirit feeds, with life and mental light, certain plants, trees, flowers, birds, insects, fish, beasts, men and women; representatives of living creatures in varying stages of evolution. It inspires souls who are on various planes, various levels of consciousness in the After-death. It feeds also creatures on other planets. For the spirit must gather a harvest of experience in every form."
Cummins, Geraldine. The Road to Immortality. London: Ivor Nicholson & Watson, 1932.