After dissecting each phrase in Rashi's seemingly unnecessary comment, and the teaching us the halachic outcome of this Rashi, the Rebbe goes on to teach us its lesson in life:
Rashi teaches us, that in order to be purified, or to help others be purified, before G-d, one must remove his virtuous spiritual garments of honor and glory.
Rather, one must enter into the Holy of Holies of his soul, which can only be entered into via the simplicity of being “ordinary”.
That is how the essence of Yom Kippur works