וזהו שכתוב: תמיד עיני ה׳ אלקיך בה
And this is the meaning of the above-quoted verse, "Forever are the eyes of the L‑rd your G‑d upon it,"
שהעינים הם כינוים להמשכת והארת אור החכמה
for "eyes" is an epithet for the efflux and radiation of the light of Chochmah,
שלכן נקראו חכמים: עיני העדה
for which reason sages are referred to as1 "the eyes of the congregation," for they are illumined by the light of Chochmah which is known by the epithet "eyes".
ואוירא דארץ ישראל מחכים
And [this, too, is the meaning of the teaching],2 "The atmosphere of the Land of Israel makes one wise" — for the Land of Israel, too, is illumined by Chochmah.
As was stated above, "Forever are the eyes of the L‑rd your G‑d upon it" refers to a constant illumination by Chochmah.
והארה והמשכה זו, אף שהיא תמידית
Now, this radiation and efflux, though it is continuous,
אף על פי כן אינה בבחינה ומדריגה אחת לבדה מימי עולם
nevertheless, it is not only on one and the same plane and level since the beginning of the world.
אלא שבכל שנה ושנה הוא אור חדש עליון
Rather, every year there is a new and superior light,
כי האור שנתחדש והאיר בראש השנה זה, מסתלק בערב ראש השנה הבאה, לשרשו
because the light which was generated and which shone on this Rosh HaShanah withdraws to its source on the eve of the next Rosh HaShanah.
וזהו שכתוב: מרשית השנה ועד אחרית שנה לבדה
This enables us to understand the verse that says that "the eyes of G‑d" are upon the Land "from the beginning of the year to the end of the year" only.
The verse does not state that they are there "everlastingly", for the efflux that descends on Rosh HaShanah lasts only to the end of the year, at which time it withdraws and makes way for the descent of a new and more sublime light.
ולכן כתיב: מרשית, חסר א׳
And that is why meireishit ("from the beginning") is written without an alef:
רומז על הסתלקות האור
it alludes to the withdrawal of the light, signified by the alef,3
שמסתלק בליל ראש השנה
which withdraws on the night of Rosh HaShanah
At that time the innermost element of the world's vitality is in a state of withdrawal due to the "ascent of Malchut"; i.e., the innermost core of Malchut is then in a state of elevation and withdrawal,
עד אחר התקיעות
until after the sounding of the Shofar,
שיורד אור חדש, עליון יותר, שלא היה מאיר עדיין מימי עולם
when there descends a new and more sublime light that has never yet shone since the beginning of the world.
והוא מתלבש ומסתתר בארץ החיים שלמעלה ושלמטה
It vests itself and conceals itself in the Eretz HaChayim which is above — i.e., in Malchut of Atzilut, the source of all worlds and created beings — and in the Eretz HaChayim which is below, in the Land of Israel,
For the light that animates this world first passes through the Holy Land, and from there it is diffused throughout the world at large.
להחיות את כל העולמות כל משך שנה זו
in order to animate all the worlds for the duration of that year.
אך גילויו מההסתר הזה
Its manifestation, however,
For the light became concealed in the Eretz HaChayim above and below, so that its further descent and the revelation of its creative life-force to the world and to all its created beings:
תלוי במעשה התחתונים, וזכותם ותשובתם בעשרת ימי תשובה
depends on the actions of those below, and on their merits and penitence during the Ten Days of Penitence.
ודי למבין
This will suffice for the initiated.
In summary: The Divine light issuing from the Sefirah of Chochmah in the World of Atzilut that radiates within the Land of Israel throughout the year, increases yearly both in quantity and in quality. Similarly, the tzedakah given for the Holy Land should be increased every year both quantitatively and qualitatively.
The conclusion of the above letter makes it clear that this mortal initiative makes an impact on the revelation of this light: the ever-increasing revelation of the light that descends in a concealed form is dependent on the ever-increasing contributions of tzedakah given for the Land of Israel.