Unity below sustains the heavenly palace

בפסוק אספה לי שבעים איש כו' ובמד' הבונה בשמים מעלותיו ואגודתו על ארץ יסדה לפלטרין בנוי על גבי ספינות כו'.

On the pasuk: "Gather to Me seventy men..." (Bamidbar 11:16), and in the Midrash: "He who builds His upper chambers in the heavens and founds His bundle (agudaso) upon the earth" (Amos 9:6) — [this is compared] to a palace (palterin) built upon ships... etc.

The Midrash on the command to gather seventy elders draws on the pasuk picturing Hashem's heavenly structure resting on an earthly "bundle," likened to a palace built atop a fleet of ships bound together.

אספה לי הוא כניסי' שהיא לשם שמים שכשמתאספים בנ"י לשמו ית' בעבור כי יודעים כי הבנין בשמים תלוי בהם וזהו לשם שמים.

"Gather to Me" (asfah li) is a gathering (kenisah) that is le-shem Shomayim (for the sake of Heaven) — for when Bnei Yisrael gather for His Name, because they know that the building in the heavens depends on them, that is "for the sake of Heaven."

"Gather to Me" denotes an assembly devoted purely to Hashem's sake. Bnei Yisrael gather "for His Name" out of the awareness that the heavenly edifice rests upon their unity below — and that awareness is precisely what makes it le-shem Shomayim.

אז סופה להתקיים פי' שמעוררין את השורש למעלה שזה הסוף והתכלית המבוקש מכל עבודת האדם.

Then "its end is to endure" (Avos 4:11, on a gathering that is le-shem Shomayim) — meaning that they arouse the root above, which is the end (sof) and ultimate purpose (tachlis) sought from all of a person's avodah.

The Mishnah's promise that such an assembly "will endure" (sofah le-hiskayem) is read as: they awaken the supernal root, and reaching that root is the very goal and culmination of all human service.

והבורא ית"ש קשר דברים רוחניים במעשה התחתונים.

And the Creator, may His Name be blessed, bound spiritual matters to the deeds of those below.

Hashem deliberately linked the lofty spiritual structures above to the actions of human beings here below.

ולא עוד רק כל מה שיורדין יותר בגלות ומתחזקים בתורתו ית' מעוררין עוד יותר.

And moreover, the further they descend into galus while strengthening themselves in His Torah, the more they arouse [the root above].

Not only does action below affect above, but the deeper the descent into exile — when met with greater devotion to Torah — the more powerfully it awakens the supernal root.

וז"ש כי אותן הזקנים שסבלו העבודה במצרים ומוכים בשביל בנ"י.

And this is the meaning [of the seventy]: that those very elders (zekeinim) had suffered the labor in Mitzrayim and were beaten on behalf of Bnei Yisrael.

The seventy elders chosen were the ones who had borne the suffering of the Egyptian bondage, having been beaten as foremen for the sake of their fellow Jews.

זכו עתה לתקן מה שגם מרע"ה אמר לא אוכל כו' שהוא איש האלקים בחי' שמים ממש.

They merited now to repair that which even Moshe Rabbeinu said, "I am not able [to bear this people alone]..." (Bamidbar 11:14) — he who is "the man of God" (ish ha-Elokim), the aspect of the heavens themselves.

Through their earlier suffering, these elders earned the ability to share the burden that even Moshe — the "man of God," who represents the heavenly dimension itself — declared he could not carry alone.

וע"י האסיפה בחי' אגודתו על ארץ נתיסד הפלטין וחזקו כביכול כחו של משה רבינו ע"ה כמשל המד' שהפלטרין תלוי בקשירות הספינות:

And through the gathering — the aspect of "His bundle upon the earth" — the palace was founded, and they strengthened, as it were, the power of Moshe Rabbeinu, as in the parable of the Midrash that the palace depends on the binding together of the ships.

Their assembly was the earthly "bundle" upon which the heavenly palace rests; by uniting, they reinforced even Moshe's own power — just as the Midrash's palace stands only because the ships beneath it are lashed firmly together.

Summary: Drawing on the image of a palace built upon bound-together ships, the Sefas Emes explains "Gather to Me" as an assembly le-shem Shomayim: when Bnei Yisrael unite for Hashem's Name, knowing the heavenly edifice depends on their unity below, they arouse the supernal root — the ultimate purpose of all avodah. Hashem bound the spiritual realm to human deeds, so that descent into galus met with devotion to Torah awakens that root all the more. The seventy elders, who had suffered for Bnei Yisrael in Mitzrayim, merited to share the burden Moshe could not bear alone; through their unified gathering — the earthly "bundle" — the palace was founded and even Moshe's own power was strengthened.