This shall be an anointing oil sacred to Me throughout the ages. It must not be poured on any person’s flesh. (E. 30:32)
What is the problem with pouring on flesh, basar?
In the Torah, basar is specifically used to refer to the flesh of a torso, and specifically the relationship between a man and a woman. Here are the first two uses:
So G-d cast a deep sleep upon the Human; and, while he slept, [G-d] took one of his sides and closed up the flesh at that site. (G. 2:21)
Hence a man leaves his father and mother and clings to his wife, so that they become one flesh. (G. 2:24)
And then mortality:
G-d said, “My breath shall not abide in humankind forever, since it too is flesh; let the days allowed them be one hundred and twenty years.” (G. 6:3)
None of these elements has a place in G-d’s house! Man’s animalistic desires do not belong there, and neither do reminders of our mortality.
So when we anoint with the oil, hearkening back to Jacob’s first acknowledgement of the holiness of the gateway to heaven, we do it as Jacob did: on the head. The head is the home of man’s spiritual self, our thoughts and emotions, our higher-order mental functions, the nostrils through which we were ensouled with a divine spark.
Every animal has a body. It is mankind’s head that makes us capable of being more than mere animals, of connecting to and relating with G-d. And in the Mikdash, it is the head that leads the actions of our body, not the other way around.