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.
Link: More on Shimon
On December 23 (21 Teves), 1690, 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).
Thoughts can give life. Thoughts can kill.
For example, a soldier. The Torah commands a soldier at war, “Do not allow your heart to weaken. Do not fear. Do not panic.”
Imagine this: An army is racing towards you. Your eyes have witnessed their savagery. How can you command your heart not to fear?
Maimonides explains: Don't think those thoughts and you will not fear. Dodge them as you dodge a flying arrow.
Because such thoughts threaten not only your life, they endanger the entire nation.
A soldier must think only one thought: What must I do right now?
Today, we are all soldiers.