Our Gemara on Amud Beis teaches us that unlike the other sons of Elazar, Pinchas did not receive the elevated status of priesthood until after the incident in which he avenged Zimri’s transgressive behavior in cohabiting with the Midianite princess Kuzbi. He was already born before Aharon and his sons (including Pinchas’ father, Elazar) were anointed, so the aura that was passed down to Elazar’s children was not given to Pinchas.

We cannot conceptualize this as an inheritance, because then it should have been passed on like an inheritance, which Pinchas was entitled to as any other son. Rather, it was a kind of spiritual activation that occurred to Elazar, and once having occurred, became something to pass on through birth, - a birthright instead of an inheritance.

When did Pinchas merit the priesthood? Only after his zealotry against Zimri. But how was this enacted? There is a fascinating Zohar (III:217a) which implies that Pinchas incorporated into his soul the recently departed souls of Nadav and Avihu, Aharon’s two sons who died when bringing the “strange fire” (Vayikra 10:1) into the Holy of Holies. Pinchas’ soul became piggy-backed with Nadav and Avihu, therefore becoming an actual Cohen.

The kabbalistic idea that a reincarnated soul can join up with an existing soul is known as Sod HaIbbur. Sod HaIbbur literally translates as the “Secret of the Leap Year” and is a borrowed term referring to an embryonic addition or growth. Our ancient sages possessed a secret mathematical tradition of how to calculate when to make a leap year, also known as Sod HaIbbur. However, this borrowed term here refers to a mystical secret having to do with the way in which one soul can join another soul, by a form of benign possession.

The Gemara in Chagigah (15b) speaks of how Rabbi Yochanan had the ability to pull the infamous apostate, Elisha ben Avuya, out of Gehenom. Ben Yehoyada asks: How is this fair or just? He answers that Elisha ben Avuya was not getting off scot-free; rather, it means that he would be reincarnated. However, due to his extremely corrupted state, he might not have been able to overcome his challenges even as a reincarnated person without extra help. Rabbi Yochanan offered to piggy-back on Elisha ben Avuya’s soul, via Sod HaIbbur, and assist him in his mission in life.

This mystical idea can involve a partial reincarnation, but not a full one. It is a temporary possession—or enhancement—of a person’s soul from one or many other souls, possibly ancestors. There can even be multiple soul possessions while both are still alive in other bodies (see Rav Chaim Vital, Shaar HaGilgulim, Introduction 4 and chapter 5, as well as Magid Meisharim, Vayishlach).

We cannot understand these ideas in the fullest sense, but psychologically we can relate to them on a symbolic level. How many times have we been so inspired by an idea or a person that we feel possessed? In what ways do our ancestors’ experiences inspire or even drive us, consciously or unconsciously? Science does not give these experiences formal names, but they are subjectively meaningful and real when we feel such stirrings.

It occurs to me that if Pinchas did take on Nadav and Avihu’s souls, perhaps this was a tikkun and proper channeling of their impetuous spiritual impulse. Nadav and Avihu went too far in their exuberance during a holy ecstatic moment, offering a strange and inappropriate fire. Pinchas was also a zealot, acting beyond the letter of the law to defend the honor of the Torah (see Sanhedrin 82a), but he did so appropriately. If this is correct, then in this case the Sod HaIbbur served as a correction for the guest souls rather than the host soul.