Teshuvah renews the Ten Utterances of creation

עשרת ימי תשובה הם נגד עשרה מאמרות.

The Ten Days of Teshuvah correspond to the Ten Utterances [of creation].

The Aseres Yemei Teshuvah parallel the asarah maamaros with which Hashem created the world.

ואיתא צדיקים מקיימים העולם שנברא בעשרה מאמרות.

And it is brought that the tzaddikim sustain the world that was created with the Ten Utterances.

Chazal teach that the righteous uphold the existence of the world that was brought into being through the ten maamaros.

ואיתא במקום שבע"ת עומדין אין צדיקים גמורים יכולין לעמוד.

And it is brought: "In the place where baalei teshuvah (penitents) stand, even complete tzaddikim cannot stand."

Chazal state that those who return through teshuvah reach a level that even wholly righteous people cannot attain.

כי הצדיקים מקיימים כו'.

For the tzaddikim sustain [the world]...

The tzaddik's role is to maintain and preserve the existing creation of the ten utterances.

ובעלי תשובות חוזרין ומחדשין העשרה מאמרות.

But the baalei teshuvah renew the Ten Utterances anew.

The penitent goes beyond merely sustaining creation - he actually renews and re-creates the ten utterances, which is a higher accomplishment.

דמאחר דרשעים מאבדין העולם שנברא בעשרה מאמרות א"כ כשהרשע שב בתשובה מחדש העשרה מאמרות.

For since the wicked destroy the world that was created with the Ten Utterances, therefore when the wicked one returns in teshuvah he renews the Ten Utterances.

Sin tears down the world of the ten maamaros; so when a sinner does teshuvah, he restores and re-creates that very world he had been undermining.

ובתחלת השנה מתחדש הבריאה לכן עשי"ת מסייעין לתשובה שבע"ת צריך להתחדשות העשרה מאמרות:

And at the beginning of the year the creation is renewed; therefore the Ten Days of Teshuvah assist teshuvah, for the baal teshuvah requires the renewal of the Ten Utterances.

Since Rosh Hashanah renews all of creation, these ten days are uniquely suited to teshuvah - the penitent needs exactly this renewal of the ten utterances, which the season provides.

Summary: The Ten Days of Teshuvah correspond to the Ten Utterances of creation. While tzaddikim merely sustain the world created by those utterances, the baal teshuvah does something greater - he renews and re-creates them, repairing the very world that sin had torn down. This is why penitents stand higher than complete tzaddikim, and why these days, when all creation is renewed at the start of the year, are especially powerful for teshuvah.