אַף עַל פִּי שֶׁתְּקִיעַת שׁוֹפָר בְּרֹאשׁ הַשָּׁנָה גְּזֵרַת הַכָּתוּב רֶמֶז יֵשׁ בּוֹ כְּלוֹמַר עוּרוּ יְשֵׁנִים מִשְּׁנַתְכֶם וְנִרְדָּמִים הָקִיצוּ מִתַּרְדֵּמַתְכֶם וְחַפְּשׂוּ בְּמַעֲשֵׂיכֶם וְחִזְרוּ בִּתְשׁוּבָה וְזִכְרוּ בּוֹרַאֲכֶם. אֵלּוּ הַשּׁוֹכְחִים אֶת הָאֱמֶת בְּהַבְלֵי הַזְּמַן וְשׁוֹגִים כָּל שְׁנָתָם בְּהֶבֶל וָרִיק אֲשֶׁר לֹא יוֹעִיל וְלֹא יַצִּיל, הַבִּיטוּ לְנַפְשׁוֹתֵיכֶם וְהֵיטִיבוּ דַּרְכֵיכֶם וּמַעַלְלֵיכֶם וְיַעֲזֹב כָּל אֶחָד מִכֶּם דַּרְכּוֹ הָרָעָה וּמַחֲשַׁבְתּוֹ אֲשֶׁר לֹא טוֹבָה...
וּמִפְּנֵי עִנְיָן זֶה נָהֲגוּ כָּל בֵּית יִשְׂרָאֵל לְהַרְבּוֹת בִּצְדָקָה וּבְמַעֲשִׂים טוֹבִים וְלַעֲסֹק בְּמִצְוֹת מֵרֹאשׁ הַשָּׁנָה וְעַד יוֹם הַכִּפּוּרִים יֶתֶר מִכָּל הַשָּׁנָה. וְנָהֲגוּ כֻּלָּם לָקוּם בַּלַּיְלָה בַּעֲשָׂרָה יָמִים אֵלּוּ וּלְהִתְפַּלֵּל בְּבָתֵּי כְּנֵסִיּוֹת בְּדִבְרֵי תַּחֲנוּנִים וּבְכִבּוּשִׁין עַד שֶׁיֵּאוֹר הַיּוֹם:
Even though the sounding of the shofar on Rosh HaShanah is a decree, it contains an allusion. It is as if [the shofar's call] is saying: “Sleepers, wake up from your sleep, and you who slumber, arise. Inspect your deeds, repent, remember your Creator. Those who forget the truth in the vanities of the moment, who devote their energies all year to vanity and emptiness which will not benefit or save: Look to your souls. Improve your ways and your deeds and let every one of you abandon your evil path and thoughts.”
For these reasons, it is customary for all of Israel to give profusely to charity, perform many good deeds, and be occupied with mitzvot from Rosh HaShanah until Yom Kippur to a greater extent than during the remainder of the year. During these ten days, the custom is for everyone to rise [while it is still] night and pray in the synagogues with heart-rending pleas until daybreak.
צָרִיךְ כָּל אָדָם שֶׁיִּרְאֶה עַצְמוֹ כָּל הַשָּׁנָה כֻּלָּהּ כְּאִלּוּ חֶצְיוֹ זַכַּאי וְחֶצְיוֹ חַיָּב. וְכֵן כָּל הָעוֹלָם חֶצְיוֹ זַכַּאי וְחֶצְיוֹ חַיָּב. חָטָא חֵטְא אֶחָד הֲרֵי הִכְרִיעַ אֶת עַצְמוֹ וְאֶת כָּל הָעוֹלָם כֻּלּוֹ לְכַף חוֹבָה וְגָרַם לוֹ הַשְׁחָתָה. עָשָׂה מִצְוָה אַחַת הֲרֵי הִכְרִיעַ אֶת עַצְמוֹ וְאֶת כָּל הָעוֹלָם כֻּלּוֹ לְכַף זְכוּת וְגָרַם לוֹ וְלָהֶם תְּשׁוּעָה וְהַצָּלָה שֶׁנֶּאֱמַר (משלי י כה) "וְצַדִּיק יְסוֹד עוֹלָם" זֶה שֶׁצָּדַק הִכְרִיעַ אֶת כָּל הָעוֹלָם לִזְכוּת וְהִצִּילוֹ.
Throughout the entire year, a person should always look at themselves as equally balanced between merit and sin and the world as equally balanced between merit and sin. If they perform one sin, they tip their own balance and that of the entire world to the side of guilt and bring destruction upon themselves.
[On the other hand,] if they perform one mitzvah, they tip their own balance and that of the entire world to the side of merit and bring deliverance and salvation to themselves and others. This is implied by [Proverbs 10:25] “A tzaddik is the foundation of the world,” i.e., one who acted righteously, tipped the balance of the entire world to merit and saved it.
Rav Kook, Orot ha-Teshuvah, 5:3
The world must come to complete teshuvah. The world is not something which stands still, but progresses and develops. And true, complete development must bring us to full physical and spiritual health, and this brings with it the living light of teshuvah.