As per the Talmud, the month of Kislev marks the onset of the winter season in the Holy Land and is the third month of the "Season of the Rains."
Link: Winter
For the first time since suffering a major heart attack five weeks earlier, on the eve of Shemini Atzeret, the Rebbe left his office in 770 Eastern Parkway and returned to his home, signaling his recovery. Chassidim all over rejoiced at the good news.
From that day on, the Rebbe redoubled his efforts on behalf of the Jewish nation and all of humanity, and for the dissemination of Torah and chassidism. From then on, the first of Kislev is celebrated as a day of thanksgiving and rejoicing.
Link: Illness and Challenge (from the timeline "biography of ideas" in Therebbe.org).
Today is the second of the two Rosh Chodesh ("Head of the Month") days for the month of Kislev (when a month has 30 days, both the last day of the month and the first day of the following month serve as the following month's Rosh Chodesh).
Special portions are added to the daily prayers: Hallel (Psalms 113-118) is recited -- in its "partial" form -- following the Shacharit morning prayer, and the Yaaleh V'yavo prayer is added to the Amidah and to Grace After Meals; the additional Musaf prayer is said (when Rosh Chodesh is Shabbat, special additions are made to the Shabbat Musaf). Tachnun (confession of sins) and similar prayers are omitted.
Many have the custom to mark Rosh Chodesh with a festive meal and reduced work activity. The latter custom is prevalent amongst women, who have a special affinity with Rosh Chodesh -- the month being the feminine aspect of the Jewish Calendar.
Links: The Jewish Month of Kislev
The Laws of Rosh Chodesh
How Does a Jewish Woman Celebrate Rosh Chodesh?
You are Jacob. This is the story of your soul.
As Jacob journeyed from Beersheva to Haran, so your soul journeyed from the wellspring of all souls to this formidable world.
As Jacob made a vow as he departed, so too your soul made such a vow, Jacob’s vow. She said:
“If G-d will be with me and protect me on this journey and provide me the bread of Torah wisdom to enlighten my soul, and the clothing of mitzvahs to shine light in places where it has never shone before...
“And if I make it through the turmoil of earthly life, the burdens, the passions, the anxieties, the fears, the utter noise and cacophony of a fragmented, confused universe...
“...to find the Infinite G-d in all these ways of humankind, to imbue them with my soul’s sense of divine purpose, to render them, as well, a way of knowing G‑d...
“'...then G-d will be my G-d and this stone that I have set as a monument will be the House of G‑d.' (Genesis 28:20)
“My soul will find peace within her most inner self, in the ultimate bond with the Infinite.
And the world I entered will also be redeemed, until even the stones beneath my feet and the granite of the building in which I work will cry out, “We, too, are a place for the Infinite Light to dwell!”
You are Jacob, bearer of light, warrior of peace.