Among the themes of the Book of Ruth is a fascinating subplot with mystical underpinnings touching on reincarnation and the transmigration of spiritual energies.
The story opens with Elimelech, Naomi and their two sons, Machlon and Kilyon, moving from famine-stricken Bethlehem to the diaspora of Moab. Elimelech dies soon after the move; our Sages explain that his death was a spiritual consequence of his closing his hand to the poor and leaving the Land of Israel. His sons, however, do not take the hint, and they continue to stray by marrying Moabite princesses, Orpah and Ruth.
Machlon and Kilyon are married for about 10 years, when they too die childless, of spiritual causes. Naomi, now bereft, decides to return to Bethlehem. She kisses her two daughters-in-law goodbye. Orpah returns to her Moabite mother's house, but Ruth utters her famous words: "…Where you go, I will go, and where you sleep, I will sleep. Your people are my people, and your God is my God…" (Ruth 1:16)
After a long journey on foot, the two women arrive in Bethlehem. Ruth, in the manner of the poor of Israel, begins to glean stalks of barley left behind in the field, so that she may feed her mother-in-law and herself. Ruth's modest demeanor sets her apart from other gleaners and draws the attention of Boaz, the elderly owner of the field. Boaz shares lunch with Ruth, and invites her to continue gleaning in his field.
When Naomi learns of his interactions with her, she explains to Ruth the concept of levirate marriage and points out that Boaz is in the line of relatives of possible redeemers.
It is here that the subplot begins. Levirate marriage (yibum) is a mitzvah incumbent on the brother of a married man who dies childless. In order to maintain both the soul of the deceased and the assets of the deceased within the family, the brother (or other close relative) is obligated to marry the widow and redeem his brother's property. The first of their offspring will be counted as a descendent of the deceased, and inherits the entire estate.
How does this work? How does one man's seed produce another man's child?
Rebbetzin Tehilla Jaeger teaches that since, in this world, the physical is inextricably intertwined with the spiritual, along with the physical transfer of genetic material, spiritual "genetics" are also transmitted. The Syrian-Greeks understood this idea and cruelly exploited it. During the period in which the Chanukah story took place, a Jewish bride was required by law to submit herself to the pleasure of the Greek governor before she would be permitted to marry. It was the intent of the Hellenists to use the spiritual forces inherent in their seed to tamper with the Jewish nation from the inside out. They understood that, even if she did not conceive from her night with the governor, his energy would remain inside her and manifest itself in her offspring. In this way the Syrian-Greeks hoped to hasten the Hellinization of the Jews.
Taking this concept a step further, Nachmanides explains that levirate marriage is actually a vehicle for reincarnation. Reincarnation happens when God gives a soul a second chance to fulfill its destiny. Occasionally a soul does not accomplish what it was sent to earth to achieve. If the soul achieved a critical mass of its goals, but didn't come close to its potential, then God may give it an additional opportunity. Sometimes God does this after the body dies of "natural causes," while sometimes He causes a "premature" death and whisks the soul out of the body before it can further damage itself. In both cases, God allows it to be born again to have a fresh start.
But the old soul can't be comfortable in just any new body; the placement of a soul in a specific body is carefully coordinated. Each physical body is precisely engineered to be the best container for the particular soul it houses. The soul of the deceased husband will therefore do best in a body that is as genetically close to the previous body as possible. Mystically, this is best accomplished through the seed of the deceased's brother. Creating this vehicle for the soul of the deceased is thus considered a tremendous act of kindness.
And what if either the widow or the brother doesn't want to enter into this relationship? A ceremony called chalitzah is performed before a rabbinic tribunal. The brother removes the shoe from his foot, and his name is called "the house of the one who had his shoe removed."
This occurred in the story of Ruth. The closest relative available for the redemption of Machlon's estate refused to marry Ruth, afraid to taint his lineage through marriage to a Moabite convert. His behavior was viewed in such a negative light that the verse refers to him using the pseudonym "Plony Almony" (the Jewish equivalent of John Doe) to dishonor him by not including his name in the story.
But why subject the refusing brother to a bizarre shoe-removing ceremony? What is the relationship of shoes to marriage?
The Kabbalists liken the body unto "the sole of the soul." Just as a fastidious person needs shoes to protect his feet while standing in dirt and mud, so too does the soul require a "shoe" to protect it during its sojourn in a world of physicality.
The Malbim explains that when a man dies childless, he leaves his essence within his wife, agitated and threatened by the dissolution of his name and memory. By refusing to enter into a levirate marriage, the soul of the deceased husband is denied the "shoe" he needs to reenter this world and fulfill his destiny.
This explains why Naomi instructed Ruth to go to the granary at night, lie next to Boaz and uncover his feet (Ruth 3:4). While initially her behavior might seem inappropriate, the significance of Ruth's message to Boaz was that the time had come for action: either "uncover the feet" of her deceased husband, and thwart his soul's return, or provide his soul with a "shoe" by marrying Ruth.
Ruth's dominant character trait was kindness. This led her to disregard the thought of younger, more suitable prospects for marriage, instead choosing to marry Boaz, a man who was twice her age. That's because Ruth's driving desire was to provide this vehicle for her late husband's soul.
Boaz recognized, through witnessing her other acts of modesty and kindness, that Ruth's intentions were pure, and he went along with her plan. Ruth conceived on her wedding night, and when the baby was born, the verse states that "a son was born to Naomi" (Ruth 4:17) -- thus confirming that the soul that Ruth brought into the world was indeed the reincarnation of Machlon.
The baby's name was Obed. He became the father of Ishai, whose son, David, composed the book of Psalms and became king of Israel. It is from David that all other kings of Israel, and ultimately the Messiah, will descend.
Ruth achieved tremendous spiritual heights: she attached her soul to the nation of Israel, sustained her mother-in-law, redeemed the soul of her late husband, and merited to become progenitor of he who will bring the final redemption to the world.