Rabbi Shlomo (1738-1792), Chassidic Rebbe in the town of Karlin, Russia (near Pinsk), was killed in the pogroms which accompanied the Polish uprising against Russia.
During the Three Weeks, from 17th of Tamuz to the 9th of Av, we commemorate the conquest of Jerusalem, the destruction of the Holy Temple and the dispersion of the Jewish people.
Weddings and other joyful events are not held during this period; like mourners, we do not cut our hair, and various pleasurable activities are limited or proscribed. (The particular mourning customs vary from community to community, so consult a competent halachic authority for details.)
Citing the verse (Isaiah 1:27) "Zion shall be redeemed with mishpat [Torah] and its returnees with tzedakah," the Rebbe urged that we increase in Torah study (particularly the study of the laws of the Holy Temple) and charity during this period.
Links:
The Three Weeks
On Simchat Torah we dance with our feet, not with our heads.
We are celebrating the Torah, and the Torah is something we study with our heads. But we dance with our feet, not with our heads.
If we would dance with our heads, each one would dance a different dance, each in a different space, some with friends but not with others, some as lonesome souls.
One head is higher, one is lower, one is here on earth, the other in the clouds or beyond, and some minds know only their own space that no one else can know.
But we dance with our feet, and all our feet are here on the same earth—none higher and none lower. So now we can all dance as one, with one heart, as a single being.
Now there is no loneliness, only joy.