The verse tells us that "The eyes of the Lord your God are upon it from the beginning (רשית) of the year until the end of the year" (Deut. 11:12). The mystics ask: If God's supervision spans the entire year why doesn't the verse just say 'forever'? Noting the missing letter in the word 'beginning' which is usually spelt with an aleph they infer that there is a momentary pause at the end of the year and the beginning of the new one (רשית=תשרי) when God's interaction with the world is no longer assured. From sunset on Rosh Hashana eve until the blowing of the shofar the next day we are expected to provide the justification for God to once again become the Master of the universe. (See Tanya, Iggeret ha-Kodesh, Epistle 14)
A key feature of this mystical approach is that each year there is an upgrade, it is as if the worlds had never existed before and we need to reach beyond all pre-existing categories and justifications for creation and existence. We are not trying to maintain the status quo, we are trying to keep up with God's infinite capacity to renew and regenerate. God seems capable of leaving the past behind, moving on, starting again. For some of us we find comfort in the stability of our piety and our iniquity, it reliably anchors us as we move through the year, through life. We are never vulnerable since we know how to ride the various waves that confront us. The many layers, some positive others less so, we wear during the year to justify our continued participation in the game of life, hold less currency on Rosh ha-Shana. The game stops and we are asked the question: who are you? what are you capable of becoming?
On the one hand, we need to forget the past and be open to change and transformation; however, the disposal of the past is no straightforward task. It is not as simple as screaming out the childlike primordial cry of the shofar and starting afresh. The objective is not to appear like a toddler having a tantrum. There is a profound depth of experience that accompanies the shedding of layers of consciousness, feelings, regrets, ambitions and delusions.
No doubt we will all quickly 'get dressed' after the blowing of the shofar, reassume some familiar patterns of life and the world will continue to spin on its axis. Yet, to the extent that we wish it, absolute free choice has been granted to us to change, not just to do what we want, but even to want something different.
The Haftarah begins "Return Israel to (עד) the Lord your God, for (כי) you have stumbled through your sins." (Hosea 14:2) The medieval commentators all seem to suggest that beyond the simple and straightforward reading of the verse the awkward use of עד and כי is pointing towards further insight. Rashi quotes a Midrash which highlights the two names of God in the verse. YHVH is describing God as merciful whereas Elokim is the divine name for justice. the verse is thus saying that you should return whilst/as long as/עד God is being merciful and not wait for God to become judgmental.
Chassidus explains how generally, we appreciate the idea of justice. It seems fair that those who play by the rules should be rewarded and those who don't should be punished, and we are rightly disturbed when bad things happen to good people. However, a rules based system has no room for Teshuva. Teshuva is a plea for mercy, that notwithstanding my breaking of the rules, I seek forgiveness. If we approach Elokim with such a request we might be told that the computer says no. The only way is to go higher and approach YHVH. To arouse the merciful God to give us another chance.
We don't want an exclusively merciful God with no sense of justice. We would all probably run riot. The ideal is to do Teshuva to such an extent/עד that God's mercy and justice are combined. Where we can have the best of both worlds, a system of rules with a degree of flexibility. This ideal is the premise of the Shema where we similarly try to blend the divine names and is also the messianic hope when God and God's names will be one.
How do we achieve this harmony? through Teshuva. The only way to do Teshuvah is through sinning first. Because/כי you have sinned you can do Teshuvah to such an extent/עד that YHVH is your Elokim. Of course this is not an instruction to sin, but it is an acknowledgement that to achieve a meaningful Teshuva a person must realise it is not in spite of their past but because of it. Some of us are capable of entering a zone of piety during the High Holidays where butter wouldn't melt in our mouths, and we revel in the sanctity of the liturgy and the fasting. I suspect it is a subconscious strategy to keep the other aspects of our self intact so we can go back to them as soon as the intrusion of the High Holidays has passed. For Teshuva to mean something we need to accept that iniquity is not the enemy of sanctity but its very origin. to paraphrase Mae West, when I am good I am very good, but when I am bad I can become even better. (See Sefer ha-Ma'amarim 5759, 35)