What was the first mitzvah given to the Jewish people as a whole? The answer is the mitzvah of sanctifying the new moon (kidush hachodesh); given in Egypt to us. Why is it so important? One explanation is that it shows how much spiritual power and potential we have; if we don’t declare rosh chodesh, then there is no rosh chodesh and no festivals that month; and festivals are when HaShem gives us certain spiritual opportunities and powers. Thus, this mitzvah shows our power and responsibility to the world; we must get involved in facilitating the bringing down of kedusha into this world, and the entire world can be affected by our declaring of the new chodesh. We need to know who we are and our potentials.