Why is Rosh Chodesh the first Mitzvah given to Israel while still in Egypt? Why is Parshat Hachodesh so important that it precedes the Giving of the Torah at Mount Sinai? Why do we say Hallel on Rosh Chodesh as Hallel is said to commemorate  a miraculous event such as the Exodus? What miracle takes place on Rosh Chodesh that warrants saying Hallel?
 
The Zohar, in explaining the importance of the new moon and our celebration of its renewal each month, states: "The Jewish nation is compared to the moon. Just as the moon wanes and seems to disappear into darkness only to be reborn, so toothe Jewish people often appear to be overwhelmed by the forces of darkness only to reemerge as a nation reborn."
 
The main Kabbalistic teaching about Rosh Chodesh, is its concept of renewal. Each New Moon marks a new beginning both for the individual Jew and for the Jewish people as a whole. Even the word for month (chodesh) is connected with the word new (chadash) and suggests a new start. Similarly, the date in every marriage contract (Ketubah) is given in Hebrew, although the document is in Aramaic, in order that the word chodesh be used to indicate that for the newly married couple their wedding is the beginning of a new life.
 
In addition to its being a semi-festival, as the beginning of a natural division in time, Rosh Chodesh is also regarded as a day of Teshuva (repentance)  because a sin-offering was one of the sacrifices brought on that day (Numbers 28:15). Moreover, the dimunition of the moon's light was regarded as symbolic of human guilt, and the reappearance of the moon was regarded as a sign of atonement calling for celebration. Erev Rosh Chodesh is called "Yom Kippur Katan (The Minor Day of Atonement), and is observed by some as a fast day with the recital of special prayers (selichot) and confession of sins at the Minchah service for the sins of the preceding month.
 
The combination of joy and solemnity on Rosh Chodesh is not at all inappropriate. The beginning of a new period in time is an obvious occasion when a person should take stock of his life and, since no-one is without sin as Kohelet states, it is an appropriate time for introspection and self improvement. Corresponding to the renewal which takes place on the New Moon in nature, Rosh Chodesh can be a time for renewal in one's spiritual life. Like Rosh Hashana (the first day of which is also Rosh Chodesh) the New Moon should make one conscious of the rapid flight of time, and it may impel us to use our limited time in this world wisely. By the use we makes of our time, we are to some extent its master. Thus, because Rosh Chodesh has this aspect of Teshuvah, it is a festive day. Indeed the Mishnah Brurah rules that on Rosh Chodesh we should have a Seudat Mitzvah to celebrate the opportunity of Teshuvah and renewal.
 
The Talmud states that the Jewish people are comparable to the moon, and that other nations are comparable to the sun. The great nations of the ancient world, much more powerful than Israel, arose like the sun to full brilliance, but after a while they disappeared from the world scene. The Jewish people, never as great as other nations, have nevertheless outlived mighty empires. Like the moon, the Jews have undergone many phases of persecution without being destroyed, and, phoenix-like, they have renewed themselves out of the ashes of Auschwitz. The continued existence of the Jewish people, against all odds, is a phenomenon that cannot be explained scientifically, and even secular philosophers have described the establishment of the State of Israel just three years after the Holocaust as something mysterious and miraculous.
 
Therefore, Rosh Chodesh had to be the first Mitzvah, given to us as a nation, because it gives us the awesome ability to create ourselves anew through the power of Teshuvah, thus imitating G-d, the Creator who continually renews creation. This concept of renewal is the greatest miracle of all, thereby warranting the recitation of Hallel.