Sanctifying the Body
והי' מחניך קדוש בשם <b>מו"ז ז"ל</b> שפי' מחניך על אברי האדם כו'
On the verse "And your camp shall be holy" (Devarim 23:15), in the name of my grandfather and teacher, of blessed memory, who explained "your camp" as referring to the limbs of a person, and so forth.
The Sfas Emes cites his grandfather, the Chiddushei HaRim, who read "your camp" not as a physical encampment but as the limbs of a person's own body, which must themselves be kept holy.
ה"א מתהלך הוא בחי' רוח קדושה שיש בכל איש ישראל וכפי תיקון הנפש שהוא מלבוש החיצון
The full force of "He walks about [in the midst of your camp]" (Devarim 23:15) is the aspect of the spirit of holiness that resides in every member of Bnei Yisrael, and it is drawn forth according to the rectification of the nefesh, which is the outer garment.
The verse's promise that Hashem walks within the camp points to the spirit of kedushah embedded in every Jew, and how much of it shines out depends on how refined and rectified the nefesh is, since the nefesh serves as the outer garment for that inner holiness.
כמו כן מתפשט הרוח קדושה שבנפש האדם:
In that same measure does the spirit of holiness that lies within a person's nefesh spread forth and become revealed.
To the degree that a person purifies that outer garment of the nefesh, the spirit of holiness hidden inside him is able to spread out and express itself.
Summary: The Sfas Emes builds on his grandfather's teaching that "your camp shall be holy" speaks of the limbs and body of every Jew, which must be sanctified. He explains that Hashem's presence walking within the camp corresponds to the spirit of holiness planted in every member of Bnei Yisrael. The degree to which this inner kedushah is revealed depends on the rectification of the nefesh, which functions as the outer garment clothing that holiness. When a person refines that garment, the spirit of holiness within his nefesh is able to spread forth and shine outward.