I don’t have anything to draw this together, yet, but this is what I’ve come up with. Comments are welcome.
Both days have an issur on eating, drinking, anointing, wearing leather shoes, and marital relations. Tishah B’Av
- The restrictions are because this is a day of mourning.
- Fast is on the 9th, but the majority of the destruction was on the 10th, so abstaining from wine and meat continues in to the 10th.
- On the 1st of the month, we decrease happiness (Mishnah Taanit 4:6)
- The fast is followed by a happy day on the 15th of the month, celebrating (among other things)Am Yisrael coming together as a nation (Taanit 30b).
- Am Yisrael as a nation needs to do teshuvah in order to achieve the goal of the day.
- If Am Yisrael takes an active role in the tikkun for the day, it is akin to working for the Keitz Meguleh, which is related to the Geulah B’Itah.
- The restrictions are to help us become spiritually elevated. This is not a sad day.
- Yom Kippur is on the 10th, yet it is a mitzvah to fast a little on the 9th.
- On the 1st of the month is the Day of Judgment, Rosh Hashanah.
- The fast is followed by the Time of our Happiness, on the 15th of the month. According to Rebbi Eliezer (Sukkah 27b), one must spend Sukkot in their own Sukkah, leading to a private holiday, not a public one.
- Each individual has to do teshuvah in order to achieve the goal of the day.
- If Am Yisrael does effective teshuvah, this would merit the Geulah Achishenah.