What is particularly interesting is the progression of the day. We start of by wallowing in misery about all of the catastrophes that have befallen the Jewish people. The Scroll of Lamentations is read in the evening. There are special elegies (קינות), dirges rather, that are read in morning services. However, as the day continues, the mourning practices start to let up. We put on tefillin and the tallit during Mincha, as well as hear Torah and Haftarah portions that mention G-d's Thirteen Attributes of Mercy. At the end of Tisha B'Av, we are not only permitted to eat again, but it is tradition to say Kiddush Levanah. The practices of Tisha B'Av seem to suggest something about how to deal with loss and tragedy.
During Yom Kippur services, we learn that we can only metaphorically beat ourselves up so much. Tisha B'Av recognizes a similar limitation of the fragile human soul. We can only despair so much. If we wallowed for days, it would probably be an overload. The Torah and Haftarah portions remind us that even when angry, still is a merciful G-d. Even when we are at our lowest, G-d reminds us that all is not lost. In the Mishneh Torah (Ta'aniyot 5:3), Maimonides quotes Micah 3:12, which says "Zion will be plowed like a field." Yes, the Temple was destroyed, but a field that is plowed is plowed in order to make way for new crops. I won't go as far as to put it in the public policy parlance of creative destruction, but I will say that letting up on the entire day of mourning shows mourning. Instead of despair, we can move onto consolation. From that consolation, we can begin to pick ourselves up. When faced with any tragedy or catastrophe, it is easy to stay stuck in the past. The mercy shown in these leniences is meant to give us the opportunity to get up and start anew, much like a phoenix that emerges from the ashes.
When tragedy strikes, we have to remember that once it does strike, it has already happened. As much as we wish it would not happen, it did. Our reaction to tragedy is a turning point. Some of our most important lessons come from failure or tragedy. Do we remain captive by the past? Or do we simultaneously recognize the tragedy that happened while remembering that there is, as Maimonides reminds us, a future where there can be growth and a way to grow anew? We're never the same after tragedy, but we're not destined to fail, either. Tisha B'Av is the emotional low point in which we are meant to spiritually lift ourselves up and gradually prepare for the upcoming weeks leading to the High Holy Days. Yes, tragedy strikes, but how we move forward is up to us.