The noted Kabbalist Rabbi Eliyahu ben Moshe Loanz, known as "Rabbi Eliyahu Baal Shem" of Worms, Germany, passed away on the 21st of Tammuz of the year 5396 from creation (1636 CE). He was a grandson of the famed shtadlan (Jewish activist) R. Joselman of Rosheim, and the author of Michlal Yofi commentary on Ecclesiastes.
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
The science of energy allows us to perceive the divine force that sustains the universe. There is a force we call electromagnetism.
It cannot be grasped with any of the five senses—we can know it only from its effects and related phenomena. Indeed, we cannot explain it in any other terms.
Yet it permeates all of our experience, and from it we derive great light and power.
It manifests itself in the pull of a magnet, in the light of the sun, in the waves that carry our network of communication through air and empty space, in the work performed by our machines, and in endless more phenomenon.
Yet it is one.
For its Creator is one.