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
When Torah first entered our universe through its portal on Mount Sinai, its first word was an Egyptian word: “Anochi,” meaning “I.”
And indeed, when the angels claimed that Torah belonged in their ethereal domain, Moses demanded of them, “Did you descend to Egypt? Did you set your bloody hands to form a brick from straw and clay? Have you felt the sting of a taskmaster’s whip upon your sunburnt back? How could you have Torah?”
For to have Torah is to have G-d raw.
Not G‑d as an idea for the mind to grasp, not G-d as a transcendent spirit for the soul to find. No, G-d as He is beyond any description or name. As He is simply “I.”
And where will you grasp that I?
In the Egypt of life into which you were cast from birth. In your daily struggle to preserve your integrity, to save your soul from drowning in a world that no one can explain, where G-d appears at times entirely absent.
He is there. His “I” is there. And you will find Him there, as you bring Torah into that place.
“There is one short chapter of only a few words,” teaches the Talmud, “and upon it hangs the entire Torah.”
“In all your ways, know Him.”
In your ways, in your personal Egypt. Know Him—He who is beyond all knowing.