These seven days are difficult for several reasons. One, according to science the world is around 13.8 billion years and not six/ seven days. Two, the days are unnecessary to the narrative. The Torah could simply have recorded the different items created without stating that they were created on particular days. Three, even if it was desired for the description of the creation of the world to have a literary framework, why was it days and not the phrase “G-d saw that X was good?” The phrase “G-d saw that X was good” appears seven times within the description of the creation of the world, 1:4,12,18,21,23,25,31, and would also seem to be a way of dividing the description of the creation of the world into seven groups. Or, as discussed in the Mishnah in Pirkei Avot 5:1, the creation of the word could have been divided by G-d’s statements, which appear nine times in chapter one. (The Mishnah records that the phrase appears ten times, and commentators to the Mishnah attempt to find the tenth statement by G-d.) Finally, one could ask the question of the Mishnah in Pirkei Avot, why was the world not created complete in one instance? Or, why did the Torah just not record, “G-d created the world” without any of the particular details?
The answer to all these questions is from Shemot 20:11, which is part of the Decalogue, and some people recite this verse as part of kiddush on Shabbat morning. The verse records “For in six days G-d made the heavens and the earth, the sea and all that is in it, and he rested on the seventh day; therefore (al ken) G-d gave the seventh day his blessing, and he hallowed it,” Fox translation, 1995, p. 371. This verse is similar to the last verse in the description of the creation of the world in 2:3, though 2:3 does not have the word, therefore.
The answer to all these questions is from Shemot 20:11, which is part of the Decalogue, and some people recite this verse as part of kiddush on Shabbat morning. The verse records “For in six days G-d made the heavens and the earth, the sea and all that is in it, and he rested on the seventh day; therefore (al ken) G-d gave the seventh day his blessing, and he hallowed it,” Fox translation, 1995, p. 371. This verse is similar to the last verse in the description of the creation of the world in 2:3, though 2:3 does not have the word, therefore.
Shemot 20:11 is telling us that the division of the creation of the world into seven days was in order that the seventh day, Shabbat, would be special, which occurred by G-d “resting” on the seventh day. In theory, G-d could have created the word without the framework of days, and then told the Jewish people to rest every seventh day. Yet, if this were true, the resting on the seventh day would not be related to the creation of the world. Instead, the seven day literary framework within the description of the creation of the world is to create a connection between a person resting on Shabbat and the creation of the world.
Accordingly, even if scientifically the world is 13.8 billion years, the point of the days within the description of the creation of the world is for people to make the seventh day special. Even if each day in chapter one of Bereshit is really billions or millions of years, still the usage of the word day is for people living after creation to relate the creation of the world to their normal twenty four day and seven day week. The creation of the world could not been recorded by a division of years or even periods since then there would be no connection between Shabbat and the creation of the world. Also, the phrase “and G-d saw that X was good,” could not be used as the literary framework of the description of the creation of the world since it does not relate to people keeping the Shabbat. Possibly to ensure that this phrase is not used as a literary framework, the phrase is not used on days two and seven. For the same reason, the creation of the world could not be framed around G-d’s statements, as again this would not relate the creation of the world to resting on Shabbat. Finally, for the same reason there had to be a division in the description of the creation of the world into seven days and not one instantaneous act or just one verse which stated that G-d created the world. Note this idea might be an example of the principle in the Midrash that G-d looked into the Torah when He created the world, (Bereshit Rabbah 1:1), as the description of the creation of the world in the Torah with regard to the number of days is based on people in the future observing Shabbat.
Accordingly, even if scientifically the world is 13.8 billion years, the point of the days within the description of the creation of the world is for people to make the seventh day special. Even if each day in chapter one of Bereshit is really billions or millions of years, still the usage of the word day is for people living after creation to relate the creation of the world to their normal twenty four day and seven day week. The creation of the world could not been recorded by a division of years or even periods since then there would be no connection between Shabbat and the creation of the world. Also, the phrase “and G-d saw that X was good,” could not be used as the literary framework of the description of the creation of the world since it does not relate to people keeping the Shabbat. Possibly to ensure that this phrase is not used as a literary framework, the phrase is not used on days two and seven. For the same reason, the creation of the world could not be framed around G-d’s statements, as again this would not relate the creation of the world to resting on Shabbat. Finally, for the same reason there had to be a division in the description of the creation of the world into seven days and not one instantaneous act or just one verse which stated that G-d created the world. Note this idea might be an example of the principle in the Midrash that G-d looked into the Torah when He created the world, (Bereshit Rabbah 1:1), as the description of the creation of the world in the Torah with regard to the number of days is based on people in the future observing Shabbat.
Bibliography:
Fox, Everett, 1995, The Five Books of Moses: A new translation, New York: Schocken Books