On Rosh Hashanah and Yom Kippur, we repeat the word ובכן in Shemoneh Esrei numerous times. Abudraham explains that the word comes from the pasuk (Esther 4:16) ובכן כדת לא אשר המלך אל אבוא, "And then I will go to the king..." because, on Rosh Hashanah, we come before the King, Hashem.
Rebbe Yehoshua of Belz zt'l explains that the main lesson of the pasuk is לא אשר המלך אל אבוא ובכן כדת, "and then I will go to the king, which isn't proper." The pasuk refers to sinners who may be unworthy of coming to the King. On Rosh Hashanah and Yom Kippur, they can come to the King, and Hashem accepts their tefillos.
As we say in the tefillos of Rosh Hashanah, וגדול קטן ומשוה, "Hashem acts equally towards the small and the great people."
The Imrei Chaim of Vizhnitz zt'l says that the roshei teivos of מלכיות, זכרונות, שופרות spell ז"שמ. Add one more (the kollel), and it is ח"שמ. Our greatest joy on Rosh Hashanah is that we proclaim Hashem King.
May we all be zocheh to be inscribed and signed for a good year in the sefer of tzaddik gemurim.
