LEV926 Desist from prohibited melachah on Rosh Hashanah. One of Hashem's kind acts is that once a year He reviews the deeds of each human being and on that basis issues a decree. Thereby, a person's sins do not accumulate to too great a degree and he can attain atonement. Since a person's sins over the course of only one year are relatively few in number, Hashem forgives and grants atonement for them. If grave sins have been committed so the guilty parties need purification, He extracts payment little by little. Were Hashem to wait and take the accounting of our sins only after a long period of time, our sins would accumulate to such a degree that the world would almost need to be destroyed, God forbid. It turns out that this special day--Rosh Hashanah, Judgment Day--is necessary so that the world can continue to exist. For this reason, it is fitting that it be a holiday. On the other hand, since it is Judgment Day for all creations, there should be more of a feeling of fear and trepidation, relative to the other holidays of the year. An illusion to this idea is found in the sound of the shofar, for the broken, shrill shofar blows instill fear in us and shake us to break our evil inclination, so that we will regret and repent from our sins.