ויקחו לי תרומה ה'תשמ"א.
The three תרומות in Avoda are:
1) 1) Torah, 2) Mesiras Nefesh (tefilla), 3) Mitzvos.
This is connected to the עין יפה בינונית ורעה א' ממ' א' מנו"ן וא' מסמ"ך.
2) How in Torah itself there is 1) Torah, 2) The source of Mesiras Nefesh (Tefilla), 3) the source of Mitzvos.
This second idea is the source of ירידה צורך עלי'ה in Torah and the world.
The similar notion (of ירידה צורך עלי'ה) is found in the מאמר וקבל היהודים תרפ"ז about מסירת נפש, that nowadays is represented by the idea of אל יובש מפני המלעיגים.
The word 'Li' connotes unchanging. this is understood on two levels:
1) Spiritually the Mikdash on high is forever.
2) The Shuls in Yeshivos in Galus make the Beis HaMikdash eternal.
This must be in a specific place just as the body has many different limbs and the highest (or center) is only the brain.
[Order brings real Bli gvul].
In Avoda there is Makif which is Mitzvos; two levels: reasonable and unreasonable.
and Pnimi which is Torah: two levels: Nigla and Nistar.
This Ma'amar has three levels:
1) The idea of Shamayim and Aretz in ruchniyus, it represents 1) Torah and Mitzvos, 2) Yisachar and Zevulun, 3) The two parshiyos of Krias Shma, 4) Hafrasha and Haram, 5) Yerios and the rest of the Mishkan.
2) The "new" heaven and earth that will be Leasid lavo.
The Rebbe explains what 'new' means. No level of light that shone before (in any world) can be considered "new" only "Renewed".
For it to be "new" it must be from Atzmus. From Atzmus there will be a new Heaven and earth, including Torah Chadasha.
3) But Neshamos Yisroel (their Zera and Shaim) will be the same. Because they are the ones who cause the newness and they are themselves the Etzem (now) already.
The Maamar is Yidden's request that in Golus they be as connected as they were in the time of the Beis HaMikdash.
The Beis Hamikdash was a dira bitachtonim through Torah and Maase' and now, in Golus, we hope ("Mi Yiten") to also make Him His home.
This goes beyond the idea of Keruvim ("kiAch") and has to do with "Aviacha El Beis Imi" the Home for Hashem.
This is achieved now (in Golus) with the Koach of sovev (that is represented by: A. The Kapores above both Keruvim and B.) "Mi" which is sovev Kol Almin.
The Beis hamikdash is timeless ("Li") in it's physical structure, but more so in the human heart.