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
In Torah, we mirror on earth that which G‑d performs on every plane of reality.
If so, since the Torah prohibits dislocating even a single stone of the Holy Temple in Jerusalem, how could it be that G‑d brought the entire structure to ruins?
For it would certainly be absurd to imagine that the Assyrians or the Romans had the power to set fire to G-d’s house.
It must be that this was not an act of destruction. Rather, it was the initial phase of a much greater construction, one that would be eternally indestructible.
And for that to occur, the Temple had to be temporarily leveled to its foundations and G-d’s people had to be scattered to the furthest reaches of human habitation.
Why? Because as long as there is any place in this world that considers itself outside the realm of holiness, there remains a place for the destruction of G‑d’s Temple.
But in our exile, we meet face to face all that considers itself foreign to the divine. We grasp its reins, extract its poison, and channel its power.
This third and ultimate Temple, then, will be built of the outside turned inward, of darkness taught to shine, of the other converted to the One, of the most sinister enemy transformed to a faithful ally.
No opposition will remain in the universe. And so it will last forever.
Then we will see that in truth, there was never any destruction. There was only rebuilding, growth, and eternal, deep love.