Why did G-d create the earth in seven days? why not eight? why not six?
Hi! You’re asking a very interesting question. I should say that I’m tempted to just brush it off, by giving an answer that Maimonides used in the “Guide of the Perplexed”: If it had been six or eight, you would have asked me, Why not five, seven, or nine?
But probably you’re looking for more than that!
Maybe this will help a little: The first six days of creations are organized in two groups of three. On the first day, G-d created light; on the fourth he created the lighted objects (that move in the heavens). On the second day, he arranged the waters; on the fifth he created the creatures that live in water. On the third day, he created the dry land; on the sixth he created the creatures that live on it. On the Sabbath, the seventh day, there was no creation. Rather, that was the day of completion, when G-d and his creations could rejoice in that which he had created.
Best wishes,
Michoel Reach