"How & When the 7th Day Became Shabbat" (& what that has to do with Sefirat HaOmer)

I just discovered The Torah.com:  A Historical and Conceptual Approach last week (I think via another blogger’s link), so I haven't read much of yet, but I recommend How and When the Seventh Day Became Shabbat .  (Don't forget to read Part One.)

The short version:  The word “Shabbat” may originally have referred to a Full-Moon observance, counterbalancing Rosh Chodesh (New Moon).  

This series is particularly relevant to Sefirat HaOmer, which we complete every year on the night before Shavout (for 2015, that'll be this coming Friday night)—see footnote 1 directly below:

[1] After publishing the original essay, a friend (Albert Dov Friedberg) called my attention to a possible support for this thesis. Leviticus 23:15 states that the counting of the omer should begin ממחרת השבת (on the day after Shabbat.) This obscure phrase gave rise to various sectarian interpretations. The Qumran sect and the Sadducees interpreted this to mean literally the day after Shabbat, i.e. Sunday, and assumed it referred to either the Shabbat of Chag HaMatzot [Pesach] or the Shabbat afterwards (the Torah does not specify.) The rabbis interpreted it as the day after Yom Tov, but then why would it be called the day after Shabbat? If we assume that the Priestly author was using the older term, then Shabbat would refer to Full-Moon precisely when the first day of Passover fell ( the 15th of Nisan). The next day would then properly be called “the day after Shabbat”! Interestingly, this actually supports the rabbinic position, against those who began counting the Omer on Sunday. (The rabbinic position is also supported by the account of the first Pesach in the land in Joshua 5:11-12 – but a discussion of this would lead us too far afield.) See also the discussion, and the quote of Beer’s words, in Theophile James Meek, “The Sabbath in the Old Testament,” Journal of Biblical Literature 33 (1914): 201-12.

From Parshat Emor:

Leviticus Chapter 23

טו  וּסְפַרְתֶּם לָכֶם, מִמָּחֳרַת הַשַּׁבָּת, מִיּוֹם הֲבִיאֲכֶם, אֶת-עֹמֶר הַתְּנוּפָה:  שֶׁבַע שַׁבָּתוֹת, תְּמִימֹת תִּהְיֶינָה.	15 And ye shall count unto you from the morrow after the day of rest [Hebrew:  "Shabbat"], from the day that ye brought the sheaf of the waving; seven weeks shall there be complete;
טז  עַד מִמָּחֳרַת הַשַּׁבָּת הַשְּׁבִיעִת, תִּסְפְּרוּ חֲמִשִּׁים יוֹם; וְהִקְרַבְתֶּם מִנְחָה חֲדָשָׁה, לַיהוָה.	16 even unto the morrow after the seventh week [*] shall ye number fifty days; and ye shall present a new meal-offering unto the LORD.

*The Hebrew word used is "Shabbat," not "shavuah (week). "

[Side note:  As a person with a BA in a foreign language, it annoys me when translators "cheat."  Keep your agenda to yourself, pal.]

From my perspective, this is a case of weaving together more than one received tradition and leaving what I call "visible seams," that is, making no attempt to reconcile the different traditions. (The classic case is, as stated in the linked post, Parshat B'reishit, which recounts two completely different creation stories.)  On one hand, Shabbat, according to this understanding, originated as a Full-Moon observance, and, in the case of Sefirat HaOmer, "mochorat haShabbat (the day after Shabbat/Full Moon)” would, indeed, fall the day after the full moon. On the other hand, the very same mitzvah (commandment) tells us to count seven "Shabbatot," and states quite clearly that the day after that count would be 50 days. If the only meaning of "Shabbat" were "Full Moon," seven Shabbatot would be seven months, not seven weeks!  No wonder there was a machloket (dispute) about when to begin Sefirat HaOmer--the ancients had to determine how to observe a mitzvah in which the word Shabbat had two completely different meanings!