Shortly before sundown on the 29th of Adar, G-d commanded Moses regarding the mitzvah of sanctifying the crescent new moon and establishing a lunar calendar. This is the first mitzvah the Jews were given as a nation.
Moses had difficulty envisaging the moon's appearance at the exact moment of its monthly rebirth. After the sun set, G-d showed Moses the crescent new moon of the new month of Nissan, showing him the precise dimensions of the moon at the moment the new month is to be consecrated.
For the generations that followed, each new month was ushered in when two witnesses testified before the Sanhedrin (rabbinic supreme court) that they had seen the molad, the new moon. In the 4th century CE, Hillel II foresaw that the Jews would no longer be able to follow a Sanhedrin-based calendar. So Hillel and his rabbinical court established the perpetual calendar which is followed today -- until Moshiach will come and reestablish the Sanhedrin.
Links::
Lunar Time
Rosh Chodesh
The Molad
A few months after its creation, Napoleon's "Sanhedrin" (rabbinical supreme court) was dissolved. The Sanhedrin was created to approve certain religious regulations requested by the French "Assembly of Notables." The regulations were designed to blur the distinction between Jews and non-Jews.
The rulings of this pseudo-Sanhedrin were never adopted by Jewish communities.
Link:: Napoleon Bonoparte
Sometimes you look at yourself in the mirror and you feel unqualified. You know yourself, your failures and your faults, and you don't feel like you could be a model for others.
You say, "I should teach others? I should provide guidance?!"
So we tell you, “Yes. Because that is your place upon this planet: We live in a time when all those who know Alef must teach Alef and those who know what comes after Alef must teach that too.”
“And G‑d Above, who formed you and put you in the here and now, He knows who you are and how you are and what you are capable of accomplishing. If He believes in you, you must as well.”
Teach others and become great.