After nearly a month of fierce fighting inside Jerusalem (see "Today in Jewish History" for Tammuz 9), the armies of King Nebuchadnezzar of Babylonia broke through into the Temple compound, where they feasted and vandalized until the afternoon of Av 9, when they set the Holy Temple aflame.
Links: The Destruction of the Holy Temple
During the “Nine Days" from Av 1st to the Ninth of Av, we mourn the destruction of the Holy Temple. We abstain from meat and wine, music, haircutting, bathing for pleasure, and other joyous (and dangerous) activities. (The particular mourning customs vary from community to community, so consult a competent halachic authority for details.)
Consumption of meat and wine is permitted on Shabbat, or at a seudat mitzvah (obligatory festive meal celebrating the fulfillment of certain mitzvot) such as a brit (circumcision), or a siyum celebrating the completion of a course of Torah study (i.e., a complete Talmudic tractate). The Lubavitcher Rebbe, of righteous memory initiated the custom of conducting or participating in a siyum on each of the Nine Days (even if one does not avail oneself of the dispensation to eat meat).
Citing the verse "Zion shall be redeemed with mishpat [Torah] and its returnees with tzedakah," (Isaiah 1:27) 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:
Nine Days laws and customs
Daily live siyum broadcasts
Learn about the Holy Temple in Jerusalem
There are those who say that before we do any mitzvah, we must first understand why it needs to be done. Why else were we given a mind?
There are others who say we must just obey with simple faith. How else can we bond with One who is entirely beyond our understanding?
Abraham did both. He began with absolute faith, even when it was impossible to make sense of what he had been told to do. Yet he would not leave until his questions were answered and he had been given a way to understand.
“Don’t do a thing to the young man, for now I know that you are a G‑d fearing person.” (Genesis 22:12)
Abraham said to G‑d, “Let me present my case. First You told me that my descendants will be from Isaac. Then You told me to take him for an offering. Now You say I mustn’t do a thing to him…” (Rashi, citing Midrash)
That makes sense. Matters that are beyond our understanding can never be fit neatly into human reason. But neither can they be left in conflict.
Because if what you believe is true, it must be true everywhere. Even within your own limited human mind.