Torah unites Yisrael at their roots

בפסוק תורה צוה כו' מורשה קהלת יעקב שע"י התורה נמצא האחדות בישראל.

On the pasuk, "Torah did [Moshe] command us... an inheritance of the congregation of Yaakov" (Devarim 33:4) — that through the Torah unity is found among Yisrael.

The Torah is the "inheritance of the congregation of Yaakov" — it is what binds all of Bnei Yisrael into one unified community.

כי כל ישראל יש להם חלק בהתורה וע"י התורה מתאחדין.

For all of Yisrael have a portion in the Torah, and through the Torah they become united.

Since every Jew possesses his own share in Torah, the Torah serves as the common ground that joins them all together.

ואז שורה השכינה ביניהם כמ"ש ויהי בישורון מלך בהתאסף ראשי עם.

And then the Shechinah rests among them, as it is written, "And He was King in Yeshurun when the heads of the people gathered" (Devarim 33:5).

When Bnei Yisrael unite through Torah, the Shechinah dwells in their midst — Hashem's kingship is established precisely when the people gather as one.

היינו השרשים שיש לכל איש ישראל בתורה.

That is, the [unity of] the roots that each individual Jew has in the Torah.

The "gathering of the heads of the people" refers to the joining of the spiritual roots that each Jew possesses within the Torah — the deepest level of their unity.

וגם זה אמת שעל ידי האחדות זוכין לתורה.

And this too is true — that through unity one merits the Torah.

The relationship runs both ways: Torah creates unity, but unity in turn makes Bnei Yisrael worthy to receive Torah.

אך יש ב' מיני התאספות.

However, there are two kinds of gathering.

The Sefas Emes now distinguishes between two levels of coming-together, which will map onto Sukkos and Shemini Atzeres.

והנה חג הסוכות נקרא חג האסיף וזוכין אח"כ לתורה בשמ"ע.

Now, the festival of Sukkos is called "the Festival of Ingathering," and afterward, on Shemini Atzeres, they merit the Torah.

Sukkos, the "Festival of Ingathering," is the first, outer gathering; through it Bnei Yisrael then merit the Torah on Shemini Atzeres / Simchas Torah.

ואז יש אחדות פנימי יותר.

And then there is a more inner unity.

Shemini Atzeres brings a deeper, more inward unity than the gathering of Sukkos itself.

וע"ז נאמר עצרת תהי' לכם.

And about this it is said, "It shall be a gathering [atzeres] for you" (Bamidbar 29:35).

"Atzeres" denotes this inner gathering reserved "for you" — for Bnei Yisrael alone.

שהוא כנופיא המיוחדת רק לבנ"י התאחדות של השרשים כנ"ל.

For it is an assembly designated only for Bnei Yisrael — the unification of the roots, as above.

The atzeres of Shemini Atzeres is the intimate inner assembly in which the very spiritual roots of Bnei Yisrael are joined as one.

ואין שם מגע נכרי כלל:

And there is no foreign contact there at all.

This innermost unity is wholly exclusive to Bnei Yisrael; no outside nation can touch or share in it.

Summary: The Torah is the "inheritance of the congregation of Yaakov" that unifies all Yisrael, for each Jew has a portion in it, and that unity in turn brings the Shechinah to rest among them and makes them worthy of Torah. There are two gatherings: the outer "ingathering" of Sukkos, and the deeper inner unity of Shemini Atzeres — the atzeres reserved for Bnei Yisrael alone, where their very spiritual roots are joined with no foreign admixture.