I previously dealt with this subject in פרשת נצבים־וילך תשע״ז; this is a different approach taken from אלחנן סמט's הקהל.
Last week’s parsha had a sort of summary of the long list of laws that had been presented in ספר דברים:
Rashi understands “היום” to be figurative:
But Ramban says it is literally “today”; that was the day that Moshe finished teaching בני ישראל all the חקים and משפטים:
And this week’s parsha describes Moshe’s last day, when he gives the people his last נבואות, האזינו and וזאת הברכה.
But then, he gives them a new מצווה:
Rav Samet asks, why is this מצווה here?
But that isn’t really enough. Moshe could have said “the Torah that I will write down for you”, well before this. We already have a מצווה that refers to the completed Torah:
Rav Samet tries to understand the reason for the מצווה of הקהל:
The assembly of הקהל is a re-enactment of מעמד הר סיני, of the experience of all standing together receiving the Torah. There is a more general מצווה to teach our children about this:
Note that here מעמד הר סיני is explicitly called הקהל. We need to teach our children about the primordial הקהל. But this מצווה isn’t about telling the story, it’s about feeling it.
It is very similar to the way we experience יציאת מצרים at the סדר:
But then why add this מצווה after the נאום המצוות? Rav Samet points out that after Moshe concludes the נאום המצוות in last week’s parsha, he establishes a new ברית with the people:
And it is this ברית ערבות מואב that is invoked in the description of מצוות הקהל, not ברית סיני:
The generation that Moshe is talking to in this week’s parsha is not the generation that experienced מעמד הר סיני. They were, if they had even been there, small children. They can’t really tell their children הדברים אשר ראו עיניך. So the experience of ברית ערבות מואב is meant to give them the experience of ברית הר סיני.
It’s not a new ברית; it’s a chance for this generation to have a little bit of the feeling of what that event was like, להעמיק חוויה. And הקהל is designed to re-invigorate the people with that memory every seven years. We can’t actually re-enact ברית הר סיני. But we can re-enact ברית ערבות מואב. It’s a little similar to our סדר which is a re-enactment of קרבן פסח which is itself a re-enactment of פסח מצרים.
So that explains why the מצווה is after השלים משה לבאר את התורה; needs to be after the ברית that concluded that list of מצוות. Since the emphasis is on the experience, not the textual learning, Moshe demonstrates what הקהל is supposed to be: What we are doing today, you will continue to do in the future.
And that explains why this ceremony takes place in the year after שמיטה. Normally, סוכות is the holiday of Thanksgiving after a bountiful harvest. But after שמיטה, there is no harvest. The Thanksgiving is for being supported directly by divine providence, and so it is inherently a re-enactment of the experience of בני ישראל after 40 years in the wilderness.
We don’t have הקהל now, and we don’t feel the deprivation of שמיטה, but we can still try to feel a little of that with the celebration of completing the Torah on שמחת תורה: היום הזה ה׳ אלקיך מצוך לעשות את החקים האלה ואת המשפטים: בכל יום יהיו בעיניך חדשים.