Why the enemy appears within the song
Before the redemption, the Torah already says that the people believed:
וַֽיַּאֲמֵן הָעָם וַֽיִּשְׁמְעוּ כִּֽי־פָקַד ה׳ אֶת־בְּנֵי יִשְׂרָאֵל וְכִי רָאָה אֶת־עׇנְיָם וַֽיִּקְּדוּ וַיִּֽשְׁתַּחֲוֽוּ׃
The people believed. They heard that Hashem had remembered the children of Israel and had seen their suffering, and they bowed and prostrated themselves. (Shemos 4:31)
At the sea, the Torah speaks of belief again:
וַיַּרְא יִשְׂרָאֵל אֶת־הַיָּד הַגְּדֹלָה אֲשֶׁר עָשָׂה ה׳ בְּמִצְרַיִם וַיִּֽירְאוּ הָעָם אֶת־ה׳ וַֽיַּאֲמִינוּ בַּֽה׳ וּבְמֹשֶׁה עַבְדּֽוֹ׃
Israel saw the great hand that Hashem had exercised against Egypt. The people feared Hashem, and they believed in Hashem and in Moshe His servant. (Shemos 14:31)
What has been added? The Sfas Emes describes a recognition that reaches back over the whole course of the exile. At the sea, they could see how Hashem's rule had become known through what they had passed through. Their song could therefore include even the enemy's pursuit:
אָמַר אוֹיֵב אֶרְדֹּף אַשִּׂיג אֲחַלֵּק שָׁלָל תִּמְלָאֵמוֹ נַפְשִׁי אָרִיק חַרְבִּי תּוֹרִישֵׁמוֹ יָדִֽי׃
The enemy said, “I will pursue, I will overtake, I will divide the spoil; my desire shall be filled with them. I will draw my sword; my hand shall destroy them.” (Shemos 15:9)
Why recount that threat within a song of salvation? In Sfas Emes, Pesach 13:12 and 20:9, the recognition after the rescue extends to what came before it. The enemy's pride and the course of the exile themselves became part of the revelation of Hashem's greatness.
A person can be happy that he escaped suffering. The further level pictured here is a song that can also include what he went through. We are looking at the understanding attained in the account of redemption, without assuming that we can already explain the purpose of every difficulty in our own lives.
Who belongs in the community?
Reb Noson applies the same teaching to communal tefillah in Hilchos Kriyas Shema 2. The ketores includes chelbenah, an ingredient with an unpleasant smell:
וַיֹּאמֶר ה׳ אֶל־מֹשֶׁה קַח־לְךָ סַמִּים נָטָף ׀ וּשְׁחֵלֶת וְחֶלְבְּנָה סַמִּים וּלְבֹנָה זַכָּה בַּד בְּבַד יִהְיֶֽה׃
Hashem said to Moshe, “Take for yourself spices: nataf, shecheles and chelbenah, spices and pure frankincense; they shall be in equal proportions.” (Shemos 30:34)
The complete ketores requires its ingredients. Rambam,Hilchos Klei HaMikdash 2:8 explicitly treats omitting an ingredient as making foreign incense; the needed ingredient cannot be removed simply because its individual scent is unpleasant. Chelbenah's individual smell is no reason to remove it from the mixture. Kerisos 6b learns from its inclusion that a communal fast should include the sinners of Israel.
Reb Noson extends this to tefillah. A community that tries to gather only those who already seem righteous has missed something in the work of joining people together. The aim includes drawing the person who has fallen into the kedushah of the tzibbur. The familiar initials tzaddik, beinoni and rasha give another expression to that whole community.
The application also reaches inside each person. I come to daven with the parts of me that have served well and with the parts that need to return. I need to bring my whole self before Hashem. Leaving the shameful parts untouched at the side does not complete their repair.
This is the inner work behind the picture of the circle. A circle has no selected starting point or final end. In the application here, the person seeks a simcha that can include every part of his avodah. Things hidden away can return and disturb a passing good mood; parts brought into the work of teshuvah can acquire a different place within it.
Bringing the whole person into Shabbos
The rav says that he heard an explanation from Shlomo Carlebach many years earlier about turning around for boi veshalom during Lecha Dodi. He qualifies it as perhaps somewhat playful: that we turn to make sure we have left no part of ourselves behind. We bring ourselves into Shabbos with the burdens we have been carrying too.
That is an inward explanation of the gesture, alongside the minhag of turning to greet the Shabbos Queen. Its application is that Shabbos should receive the whole person. The rav also invokes the tradition of relief from Gehinnom's fire on Shabbos as an image of an opening that includes those who need to return; he does not examine that tradition's scope here. A part of me struggling through the week also needs to enter its rest and kedushah.
A related reading is offered of Hillel's statement at the Simchas Beis HaShoevah, “If I am here, all is here.” It hears a call to be fully present: when I come, all of me should come. Rashi explains the Gemara differently, as Hillel speaking in the Name of Hashem about the presence of the Shechinah. The inward application gives us another way to think about the completeness of our participation, while preserving that distinction.
The phrase about healing the brokenhearted supplies an associated remez:
הָרֹפֵא לִשְׁבוּרֵי לֵב וּמְחַבֵּשׁ לְעַצְּבוֹתָֽם׃
He heals the brokenhearted and binds up their wounds. (Tehillim 147:3)
The initials of harofei lishvurei lev spell Hillel. In the association offered here, the brokenhearted parts are brought into the simcha too. They are given a way to participate.
Sukkah 53a describes both chassidim and baalei teshuvah singing at the celebration. Some praised a youth that had not shamed their old age; others praised an old age that had atoned for their youth. Together they said: fortunate is one who has not sinned, and one who has sinned should return and be forgiven. The song had words for both kinds of life. The rav compares it with music's higher and lower notes: both belong to the song. This is his image of a whole life being brought into praise, not a technical rule that every possible melody must contain a particular contour.
The comparison with different parts of a person can sound close to contemporary therapeutic language. The rav repeats that he does not know much about IFS. We can understand the Torah's mashal without treating that resemblance as an identification of the two methods. Its immediate question is how a part of me that resists joy can be drawn into avodas Hashem.