the mitzvah of building a mikdash

The gemara (Sanhedrin 20) writes that when Bnei Yisrael enter Eretz Yisrael they have three mitzvos to accomplish: 1) appoint a king; 2) destroy Amalek; 3) build a beis habechirah, as the Torah tells us “V’haya hamakom asher yivchar Hashem Elokeichem… shamah tavi’u es kol asher anochi mitzaveh eschem…” (Devarim 12).  The Kesef Mishnah (Beis haBechirah 1:1) cites the SM”G who quotes this as the source for the mitzvah of building a mikdash.   The Rambam, however, quotes the pasuk of “v’asu li mikdash,” and refers not only to the building of the mikdash in Yerushalayim, but to the building of the mishkan as well.  So it sounds like we have a machlokes.

In case you missed the comments to yesterday’s post, someone pointed out that R’ Soloveitchik (essay in Koveitz Chiddushei Torah) learned that the Rambam in fact agrees with the SM”G.  The Rambam agrees that there is a mitzvah of building a beis habechirah in Eretz Yisrael learned out from the pasuk of “hamakom asher tivchar,” but the Rambam adds that there is an additional mitzvah learned from the pasuk of “v’asu li mikdash.”  “Hamakom asher tivchar” refers to the mikdash in Yerushalayim, an eternal place of kedusha; “v’asu li mikdash” refers even to building a mishkan.  This would explain the change in language that I noted yesterday.  The Rambam in his title to the halachos refers to “beis habechirah,” because he is discussing the laws as practiced in the mikdash in Yerushalayim.  However, in his list of mitzvos he refers to “beis hamikdash” and in the first halacha he refers simply to making a “bayis l’Hashem” in order to encompass the kiyum mitzvah of making a mishkan as well.

Yesterday I also noted that the Rambam switches verbs from “livnos beis hamikdash” in his list of mitzvos to “la’asos bayis l’Hashem” in the first halacha.  R’ Chaim Kanievsky (Derech Chochma) writes that “la’asos” does not mean to build – it means to see that something is done.  The mitzvah of “v’asisa ma’akeh l’gagecha” does not mean you need to take a hammer and nails and build a ma’akah.  You can hire a contractor, you can move into a house that already has the ma’akah in place – so long as there is a ma’akah there, you have fulfilled the mitzvah.  In that same way, “v’asu li mikdash” does not mean you need to take a hammer and nails and build something.  It means you need to help ensure that there is a mikdash built, whether it is by helping in the planning, contributing money, or doing anything else that helps complete the project. 

The Rambam writes (1:12) that construction of the mikdash can only be done during the daylight hours and cannot be done on Shabbos or Y”T.  In that very same halacha, the Rambam says that women are chayavos in the mitzvah as well as men.  If the mikdash can only be built at certain times, why is it not a mitzvas aseh she’hazman gerama – why are women not exempt?  R’ Chaim answers that although the actual construction, the “livnos,” can only be done at specific times, the “la’asos” of participating in other ways has no time boundary.

What remains unclear to me still is why the Rambam would use the term “livnos” in the mitzvah list if the mitzvah is really “la’asos,” with different gedarim, as R” Chaim sets out.  It is tempting to try to shoehorn this issue into the previous discussion and say that the mitzvah of “livnos” applies to beis habechirah, but “la’asos” is a din in “asu li mikdash.”  I don’t know of any source or reason to draw such a distinction.  I was wondering if perhaps in the list of mitzvos the Rambam wanted to define the mitzvah by its ultimate goal.  Any number of activities may be a kiyum mitzvah of “la’asos,” but ultimately there has to be a building built, or the “la’asos” has no meaning.  “Livnos” is the purpose; “la’asos" is the means.  Anyone have a better explanation?