After the death of Aharon’s sons, he is given a commandment not to get drunk when serving ה׳:
I want to look at that last pasuk, להורת את בני ישראל. That’s not what I usually think of when I think of כהנים. They do the עבודה; they’re not teachers per se. That role is what we call רבנות; it has nothing to do with the hereditary position of priesthood. But teaching does seem to have been the original intention for the role of the כהנים:
Before getting to that, I want to look at an interesting hypothesis by Rav Kaminetsky. He looks at the wording of בין הקדש ובין החל, and notes that Biblical Hebrew is different from Mishnaic Hebrew:
And then he notes that there is an apparent מחלוקת between the מחבר and the רמא about the wording of הבדלה.
And to explain that, he looks at another מחלוקת , in the wording of the ברכה for הפרשת חלה:
There is a difference between מצוות דאורייתא and מצוות דרבנן. The Torah says (דברים יג:א) לֹא תֹסֵף עָלָיו. We can’t create new מצוות. But the rabbis have the authority to create תקנות and גזרות, which in effect are new מצוות, but we need to be aware that they are not דאורייתא. We do them because of the authority of חז״ל (דברים יז:יא; על המשפט אשר יאמרו לך תעשה), not because they were commanded by הקב״ה. Rav Kaminetsky is suggesting that one way we keep the distinction is by using different languages for the ברכות; לשון תורה for מצוות דאורייתא and לשון חכמים for מצוות דרבנן. Of course, that implies that we are educated enough to be able to tell the difference! I don’t know whether he systematically went through the ברכות to see if it held up, but it hilights this important distinction.
Why is that relevant to original question? In the Tanach shiur, I pointed out that there is a summary of David’s administration, and it included כהנים:
Why are כהנים part of the government? The Torah says that for judgment, we have to look both to the שופט and to the כהן:
The kohanim are the keepers of the original ספר תורה:
And so Rav Naftali Bar-Ilan (grandson of Rav Meir Bar Ilan, great grandson of the Netziv) that this was the role of the כהנים: to preserve the text, to be the carriers of tradition, not just in ritual, but in תלמוד תורה as well:
There is a dialectic inherent in our understanding of Torah, between innovation and conservatism. An important part of Torah is what we as human beings bring into it:
But there is equally a place to say “this is what is was, this is what it always will be”.
In the terms we used above, the כהנים serve as the reminders of the distiction between מצוות דאורייתא and מצוות דרבנן. That, fundamentally, is the role of the כהן, להורת את בני ישראל את כל החקים אשר דבר ה׳ אליהם ביד משה.