I was asked why I attach so much importance to day one of Creation, and so little to day six. The answer is six-fold:
1. It was Shim'on Ben Zoma, who held on to the ancient tradition, in the oldest recorded reference to a stylistic problem in the story of Bereshit (Bereshit Rabbah 4: 6). See also Moreh Hanevuchim on this subject, and compare the Talmud Yerushalmi (Chagigah 2: 5) and the Talmud Bavli (Chagiga 14b,15a). In my analysis, after day one, Ben Zoma detects a difference: וַיֹּאמֶר אֱלֹהִים and וַיַּעַשׂ אֱלֹהִים, the way second day starts, is too different from day one.
His utterly shocking conclusion was that a different source starts at this point, the source that we know as P. In this way, he questioned scripture as it was and he shook the world, of the "Chachamim," because he had uncovered the secret. Ben Zoma had not gone crazy, as they would have it. He was a Chacham at the highest level, conversing with the Divine.
2. The (traditional) Pasuk says אֵלֶּה תוֹלְדוֹת הַשָּׁמַיִם וְהָאָרֶץ, בְּהִבָּרְאָם: בְּיוֹם, עֲשׂוֹת יְהוָה אֱלֹהִים--אֶרֶץ וְשָׁמָיִם. It mentions a day, and this is the day that HaShem created Eretz V'Shamayim. It thus solves the problem with the Pasuk as it stands, that no day is mentioned. A clear sign of editing.
3. That it is a day follows from the Pasuk itself, the creation of light and darkness leads to morning and evening, one day. The other days don't have this.
4. It says "one day," not "the first day." The first day would be followed by the second, the third, et cetera. One day stands by itself.
5. The one day is a reference to these 24 hours.
6. There is a reference to the words תֹהוּ and מְרַחֶפֶת, in Ha'azinu, verse 10 and 11, which has words of the same stems. Ha'azinu is a very old text. Ergo, the "one day" is very old also. See also Yeshaya 34:11.
Therefore, "one day" is part of the Torah Kedumah, the "one week" is its commentary. The two were combined by the Priestly editor of the Torah.
