Raised hands draw blessing from the supernal root

בענין נשיאות כפים כדכתיב וישא אהרן את ידיו כו'.

Concerning nesias kapayim (the priestly raising of the hands), as it is written, "And Aharon lifted up his hands…" (Vayikra 9:22).

The Sefas Emes turns to the avodah of Birkas Kohanim, in which the Kohen raises his hands to bless the people.

כי עיקר הברכה להמשיך שפע מן השורש העליון כדכתי' שאו ידיכם קודש.

For the essence of the berachah is to draw down shefa (Divine flow) from the supernal root, as it is written, "Lift up your hands in holiness" (Tehillim 134:2).

Blessing means drawing the Divine flow from its highest source; the raised hands are the channel through which that holy abundance is drawn down.

ובזוה"ק יתרו כתב שבנשיאות כפים נאמר החכמה תעוז כו' מעשרה שליטים ע"ש וכ"כ ביעקב אע"ה שכל את ידיו אחכימינון לידוהי.

And in the Zohar HaKadosh, parshas Yisro, it is written that of nesias kapayim is said "Wisdom strengthens… more than ten rulers" (Koheles 7:19) — see there. And so too of Yaakov Avinu, "he made his hands wise" (sichel es yadav), [the Targum renders] "he made his hands wise."

The Zohar links the raised hands to the verse about chochmah (wisdom) being stronger than "ten rulers," and to Yaakov, who crossed his hands when blessing Yosef's sons; the Targum on "sichel es yadav" says he infused his hands with wisdom. The hands, when lifted in blessing, channel supernal chochmah.

והענין הוא כי קודם החטא הי' ציור האדם גבוה ונשא מאוד.

The matter is this: before the sin, the form of man was exceedingly high and exalted.

Before the sin of Adam HaRishon, the human being stood on a lofty spiritual plane, his whole stature elevated.

וזה רמז מעשרה שליטים אשר היו בעיר.

And this is hinted at by "ten rulers who were in the city" (Koheles 7:19).

The "ten rulers" allude to the ten lofty levels man possessed before the fall — the original elevated structure of the human soul.

ומאחר שכבר עמדנו בזאת המדריגה רק שעל ידי החטא ירדנו עשר מעלות.

And since we already once stood on this level, only that through the sin we descended ten rungs —

Because mankind originally occupied that high station, and only fell ten degrees through the sin, the connection to that root is not lost but merely obscured.

יכולין להתאחז ולהתדבק בשורש הזה ולמשוך משם ברכה בכח החכמה.

— we are able to grasp hold of and cleave to this root, and to draw blessing from there through the power of chochmah.

Since that elevated root remains ours by origin, we can still reach up, attach ourselves to it, and draw blessing down from there by means of wisdom — which is exactly what occurs in nesias kapayim.

והשי"ת ברחמיו השאיר לנו זכר ממדריגות הראשונות אשר הי' לנו.

And Hashem in His mercy left us a remembrance of the original levels that we once had.

Out of His compassion, Hashem preserved for us "footholds" — vestiges of our pre-sin elevation — through which we can still reconnect to the supernal root.

בנפשות הם הכהנים עובדי ה'.

Among souls, these are the Kohanim, the servants of Hashem.

One such remembrance is in the realm of people: the Kohanim, who retain a closeness to the supernal root and therefore serve as the channels of blessing.

ובזמן הש"ק.

In the realm of time, the holy Shabbos.

A second remembrance is in time: Shabbos Kodesh, which is attached to the higher root and is a day of drawn-down blessing.

ובמקום הבהמ"ק.

And in the realm of place, the Bais Hamikdash.

A third remembrance is in place: the Bais Hamikdash, which stands connected to the supernal root.

אשר כל אלה הם מדובקים בשורש שלמעלה ומשם עיקר הברכה.

All of these are cleaving to the root above, and from there comes the essence of blessing.

Kohanim, Shabbos, and the Mikdash share one trait: each is bound to the supernal root, and it is precisely from that connection that true berachah flows into the world.

ומ"ש לעיל ביעקב שכל את ידיו בשורש שלמעלה לכן הקדים אפרים למנשה כי ראה שלמעלה בשורש עליון הוא למעלה ממנשה כנ"ל.

And as was said above regarding Yaakov, that "he made his hands wise" at the root above — therefore he placed Ephraim before Menasheh, for he saw that above, in the supernal root, [Ephraim] was higher than Menasheh, as stated.

Yaakov's wise hands perceived the spiritual roots above: even though Menasheh was the firstborn, at the supernal level Ephraim stood higher, so Yaakov crossed his hands to give Ephraim the primary blessing — an act guided by the wisdom that reads the higher root rather than the surface order.

וקצרתי בכאן ממיעוט פנאי:

I have been brief here, for lack of time.

The Sefas Emes notes that he has abbreviated the discussion due to limited time.

Summary: The priestly raising of the hands draws supernal blessing down to the world through the power of chochmah. Before Adam's sin man stood ten lofty rungs higher; though we fell, that elevated root remains ours, and Hashem mercifully left us "remembrances" of it — the Kohanim (in people), Shabbos (in time), and the Bais Hamikdash (in place) — each cleaving to the root above and serving as a channel of blessing, just as Yaakov's wise hands read the supernal root and blessed Ephraim before Menasheh.