Every Moment Anew

הלכות תפילין ה:יט

Klal Yisroel is compared to the moon, which constantly waxes and wanes.  This comparison hints to the notion that we must constantly renew ourselves at all times.  We must live every single day and moment as if it is completely new - and this certainly applies to one's avodas Hashem.  We must never age, Heaven forbid, even if we live 1,000 years, because every day is considered completely new.  All of the days of the the holy Klal Yisrael are like a month.  That is, a new existence every moment, which is the crux of a long, eternal life.

The Light of the Moon Will Be Like the Light of the Sun

קל"ה - הלכות ראש חודש ה:יב

(Painting by Marc Chagall)

The sun and the moon correspond to Moshe and Dovid HaMelech, which in turn relate to glory and kingship, which relate to Torah and prayer respectively.  As is known, the years are counted according to the cycles of the sun, and the months according to the cycles of the moon.  Therefore, on Rosh HaShanah, which is on Rosh Chodesh, the sun and the moon are like one, that is, both are equal in stature.  This relates to the idea that the "light of the moon is like the light of the sun."  This happens once the quality of prayer is increased by turning the Torah that one learns into prayer, and by praying that the Torah be sustained.

Rectification of the Moon and Prayer

קל"ה - הלכות ראש חודש א:א

Blemished prayer is a concept of a flaw within the moon.  On Rosh Chodesh, which is a time of rectification for the moon since it will begin to become full again, it is also a time for the rectification of prayer.