Because someone was glad to see me peeping in, I’ll give my answer again to the old old question which I
must’ve answered before (and this time you can keep it on file for the future if you find it helpful.)
Here’s how a simple Lubavitcher understood that The Rebbe is atzmus umehus areingeshtelt in a guf gashmi:
Every one of us has a Neshama which is (at the core of its core- yechida) a chelek Eloka mimaal mamash (Tanya Perek Beis.)
However, most of us operate on a lower level of soul for the most part:
Nefesh- action
Ruach- emotion
Neshama- intellectual
These take up the vast majority of our lives. Sometimes we get a bit of a Chaya- Emuna or Yechida- one with Hashem (usually brought out with mesirus nefesh where one feels it is impossible to separate from Hashem.) moments.
However, A Rebbe lives in tune with the deepest part of his Neshama- yechida lyechidcha at all times. He is a proper G-dly ambassador every moment of the day (which is who all Yidden are at our core.)
(There’sa sicha in 5751-5752 where The Rebbe says the metzius of every Jew is Atzmus umehus.
That’s the understanding of a simple young
Lubavitcher. Menachem Shmei added other mekoros- it’s not solely a Lubavitcher thing. The end