Shimon, the second son of Jacob and Leah and the progenitor of the Israelite tribe of Shimon, was born on Tevet 21 (according to another opinion, on Tevet 28), of the year 2194 from creation (1567 BCE), nine years after Jacob's arrival in Charan.
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On December 20 (21 Teves), 1691, strong earthquakes rattled the city of Ancona, Italy, causing numerous structures to collapse and placing its inhabitants in mortal danger. Miraculously, the Jewish quarter was spared, suffering the collapse of only one house. In commemoration of this event, the local Jewish community established that date as a day of celebration and song, while the previous day—20 Teves—would be marked yearly by fasting and charity (Or Boker, p. 48a).
Fighting evil is a very noble job when it must be done. But it is not our mission in life.
Our job is to bring in more light.