Rav Chatzkel Levenstein: Shemini: The Thickness of a Hair
The 18th of Adar is the Yahrtzeit of Rav Yechezkel (ben Yehuda) Levenstein, mashgiach of Ponevezh (1885-1974). “Moshe and Aharon came to the Tenant of Meeting, and they went out and they blessed the people, and the glory of God appeared to the entire people (Vayikra 9:23)!” Rashi explains that when Aharon saw that the Divine Presence had not rested upon the Mishkan despite the long the inauguration service, he was distraught and blamed himself, saying, “I know that God is angry with me because of the sin of the Golden Calf, and it is because of me that the Divine Presence has not rested upon Israel.” He turned to Moshe and said, “Moshe, my brother, what have you done to me that you had me embark upon the Divine Service and be you merely aided!” Immediately Moshe entered the Tenant of Meeting with him and they prayed for mercy, and the Divine Presence rested upon Israel.
It is astounding when we reflect on the fact that after the long inauguration service the Divine Presence would not rest on the Mishkan until Moshe prayed for mercy. All the work would have been for nothing if not for the small detail at the very and. All the work, all the contributions, all the prayers, all the aspirations of the people, all their desire, wouldn’t have been incomplete if not for that final prayer for mercy. A tiny detail, described in the Holy Books as the breadth of a hair.
As the Ramchal reminds us in The Path of the Just, “Two separate between that which is in pure for you and that which is pure,” meaning if an animal was slaughtered across most of its neck is kosher, but if it is just the thickness of a here short of the majority of the neck, the animal is not kosher. The thickness of a hair separates between that which is pure and that which is not. (Mimizrach Shemesh, Shemini 2)