Rosh Hashana 1:2-3

Rosh Hashana 1:2

The world is judged at four junctures: on Passover, for crops; on Shavuos, for fruits of the tree; on Rosh Hashana, the entire world passes before God like sheep before a shepherd, as per Psalms 33:15, “The One Who makes the hearts of all, Who considers all their deeds.” On Sukkos, they are judged for water.

Rosh Hashana 1:3

For six months messengers are dispatched: in Nisan because of Passover; in Av because of the fast; in Elul because of Rosh Hashana; in Tishrei, to fix the dates of the holidays [based on whether Elul was declared to be a 29-day month or a 30-day month]; in Kislev because of Chanukah; in Adar because of Purim. When the Temple was standing, they also sent messengers in Iyar because of the Pesach sheini (second Passover).