Ezra, head of the Sanhedrin and the leader of the Jewish people at the time of the building of the Second Temple, made an historic address to a three-day assemblage of Jews in Jerusalem, exhorting them to adhere to the teachings of the Torah and to dissolve their interfaith marriages (the Jewish people were on the verge of complete assimilation at the time, following their 70-year exile in Babylonia).
Links: On Intermarriage
The first printing of the "bible of Chassidism", the Tanya, the magnum opus of Rabbi Schneur Zalman of Liadi, founder of Chabad.
Links: The Longer Shorter Way; Lessons in Tanya (includes an English translation of the Hebrew text plus explanatory commentary in English)
The Rosh Hashanah ("new year") of Chassidism, marking the liberation of Rabbi Schneur Zalman of Liadi and the subsequent blossoming of Chabad Chassidism, is celebrated for two days, Kislev 19-20. (The Rebbe was released from prison on the 19th, but his full freedom was only obtained late in the evening -- Kislev 20 on the Jewish Calendar.) The two days are celebrated with farbrengens (Chassidic gatherings) and an increased commitment to the ways and teachings of Chassidism. Tachnun (supplication) and similar prayers are omitted. For more information and links, see entries for yesterday Kislev 19.
In Chabad practice, Tachanun (confession of sins) and similar prayers are omitted today.
There are three ways to bring unity between two opposites:
One
Introduce a power that transcends them both, and to which they both utterly surrender their entire being.
Externally, they now seem at peace with one other, because they are both under the influence of the same force.
But they themselves know that they are not truly at peace, and that such peace cannot endure, because their own being is simply ignored.
Two
Find a middle ground where the two meet.
The two are now at peace, but only on that middle ground
The rest of their territory remains apart, distant, without room for the other.
Three
Reach deeper, into the very essence of the two beings, and discover that at this point, in every aspect, they are no more than two expressions of the same one G-d.