The past couple of posts about this concept of “soul impregnation” - whereby the soul of a departed righteous person joins temporarily with the soul of a living person in order to aid them or fulfil a commandment together – has contained a numerous quotes.
The reason why this blog has been quoting from various books rather than summarizing the various opinions is to enable you to see the mosaic of ideas and opinions around the idea of departed souls (or parts of souls) attaching themselves to the living.
To add to the mosaic of ideas, here is an extract from “The Tree of Souls: The Mythology of Judaism” by Howard Schwartz. This is an anthology of Jewish myths and hence should not be taken literally. The quote below is from pp.333 “The Myth of Abraham” and is about the change of the Patriarch's name from Abram to Abraham (the addition of the Hebrew letter Heh to his name).
430. Abraham's Name
“...The tradition that Abraham was an astrologer was likely inspired by God's promise to Abraham: “Look toward heaven and count the stars, if you are able to count them.” And He added, “So shall your offspring be” (Gen. 15:1-5). Abraham's role as an astrologer is also affirmed by the talmudic tradition that Abraham wore a glowing stone around his neck that he used as an astrolabe to study the stars. See “Abraham's Glowing Stone,” pp.332.
The letter that Abraham receives as a crown to his his soul functions much like an ibbur, the spirit of a departed sage that fuses with the soul of a living person. Here God give Abraham the letter heh, taken from beneath the Throne of Glory, and fuses it with his soul, not only changing his name, but also his soul. Thus the change in his soul is a gift from God, which transforms him into the Patriarch Abraham.
Note that the linkage of this myth with the nullification of the power of astrological forces over a person. This grows out of the tradition that when God gave the Torah to Israel, He removed control of the starts and constellations over them, since the Torah transcends the world. This demonstrates the rabbi's recognition of the widespread belief in astrological forces and their concern that people would put their faith in these forces rather than in the Torah.
B. Bava Batra 16b; Aggadat Bereishit p. 73; Zohar 3:216a, 3:216b, Midrash ha-Ne'elam, Zohar Hadash 24d-25a...”