The של״ה הקודש was a great Kabbalist. He speaks a great deal about the struggle between the sun and the moon. The argument was initiated by the moon who felt that both luminaries should not have been of equal size. Hashem agreed and made the moon weaker than the sun. In Messianic times, the moon and sun will be equal again.
In this week's Parsha, we are taught the laws of קידוש החודש, the sanctification of the new month with the first appearance of the new moon. The moon was a symbol for the Jewish people. The fifteenth generation after the exodus from Egypt was the reign of Shlomo Hamelech. Just as the moon is at its peak on the fifteenth day, Shlomo's reign was never eclipsed (good pun) by any other time in history. On the other hand, the twenty-ninth generation was that of King Tzidkiyahu, that corresponded with the destruction of the first Temple. On the twenty ninth day of the month, the moon is barely seen.
The Rambam demonstrates his genius in the Mishne Torah and the laws of קידוש החודש. He gives complicated, detailed calculations showing how we can predict exactly and at what angle in the horizon, the new moon will first appear. קידוש החודש was the first Mitzva given in Egypt. Shabbat Shalom