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
On the Shabbat that falls on or before the 1st of Nissan, a special reading called "Hachodesh" (Exodus 12:1-20) is added to the regular Shabbat Torah reading. Hachodesh recounts G-d's historic communication to Moses in Egypt on the 1st of Nissan (2 weeks before the Exodus) regarding the Jewish calendar, the month of Nissan and the Passover offering.
Links: The Reading for Hachodesh
From the teachings of the Chassidic masters on Hachodesh
About the Jewish calendar
Haftorah in a Nutshell
This Shabbat is Shabbat Mevarchim (“the Shabbat that blesses" the new month): a special prayer is recited blessing the Rosh Chodesh ("Head of the Month") of the upcoming month of Nisan, which occurs tommorow (Sunday).
Prior to the blessing, we announce the precise time of the molad, the "birth" of the new moon. See molad times.
It is a Chabad custom to recite the entire book of Psalms before morning prayers, and to conduct farbrengens (chassidic gatherings) in the course of the Shabbat.
Links: Shabbat Mevarchim; Tehillim (the Book of Psalms); The Farbrengen
Tolerance doesn’t care. Tolerance just looks the other way and goes about its own business. Tolerance is Indifferent.
Caring is blind—the kind of caring that cares for everybody, no matter who they are, but doesn’t allow them to step outside the path your caring believes to be good for them. Caring can suffocate.
And then there is deep love. Deep love recognizes another person’s right to grow, their need to travel along a path and get there on their own—and yet has the compassion to be there for them when they are lost.
Deep love has room for a thousand private journeys.