Likutei Halakhot, Orach Chaim, Laws of Phylacteries 5:23/ליקוטי הלכות·אורח חיים·הלכות תפילין ה׳:כ״ג

1And this is the aspect of Rosh Hashanah. For Rosh Hashanah is the aspect of tefillin which are the aspect of renewal that we attain every day through sleep, when the brains are renewed in Emunah etc., which this is the aspect of Rosh Hashanah, as brought in the words of Rabbeinu z”l in the torah “Ashrei Ha`am” (LM #35), see there. For Rosh Hashanah is the aspect of the sanctity of Eretz Yisrael, as written, “Always the eyes of Hashem your God are on it from the year's heading unto the year's ending” [Deut. 11:12] , which this is the aspect if tefillin, which are the aspect of Eretz Yisrael's sanctity, the aspect of, “And it shall be, when He brings you” that is said in the tefillin's passages as mentioned. For the essence of Rosh Hashanah's sanctity is that we attain perfect Teshuvah/Return, for it is the first day of the Ten Days of Repentance. That is, that we attain renewing our days that passed in darkness, and from here onwards ad additional sanctity and devotion anew. Which this is the aspect of, “Renew upon us a good year,” that we request on Rosh Hashanah. “Renew” specifically, that we attain a new year specifically. For every year is a particular facet of the seventy facets of the Torah as mentioned. Therefore every year we need to attain entirely new faces. Living from now new life. Which this is the aspect of long life as mentioned. And this is the aspect of voluminous requesting and prayer on Rosh Hashanah for life many, many times in each prayer. As we say, “Remember us for life... Inscribe us for life... Who compassionately remembers his formations for life...” and many of the sort. For the essence of the aspect of life is the aspect of long life, mentioned, of the Blind Elder, who attained the ultimate memory perfectly as mentioned, as from his is drawn the sanctity of Rosh Hashanah, which is the aspect of the sanctity of the tefillin, which are the aspect of, “and for remembrance between your eyes” as mentioned. And therefore Rosh Hashanah is called “Day of Remembrance.” For the essence of its sanctity is from the aforementioned aspect of that Elder's remembrance. And all our request on Rosh Hashanah for life, the whole intention is for true and everlasting life, that is, the aforementioned aspect of long life. That is, to renew our life at all times, the aspect of, “Renew upon us a good year” — “renew” specifically, as said.