It's difficult to mourn the Destruction of the Temple, since most of us don't have any particular desire to engage in Temple service, and the persecution and massacres that were involved took place a very, very long time ago. Perhaps one way to relate to it is to read about the distressing phenomenon whereby our enemies today deny that there ever was a Jewish Temple in Israel - with the resultant conclusion that the Jews have no historical right to be in Israel. To quote Professor James Davila: There is an increasing practice among journalists of writing as though the existence of the ancient Jewish temples on the Temple Mount is a disputable question with two legitimate "competing narratives."
Many people tap into the mood of the day via contemplating the Holocaust. I'd like to share some recommendations for books about the Holocaust that I find particularly moving - please feel free to share other recommendations in the comments section.
Yaffa Eliach, Hasidic Tales of the Holocaust - I haven't read this in many years, but I remember it being very powerful. There's valuable mussar in the story about the survivors whom, at a wedding many decades later, asked the waiter not to clear off the table, because they still found it reassuring to see food in front of them.
Rabbi Ephraim Oshry, Responsa From The Holocaust - It's incredibly moving to see what kinds of halachic questions people were asking during this period, and how desperate they were to maintain allegiance to halachah even under the most adverse circumstances.
Victor Frankl, Man's Search for Meaning - A classic. Everyone should read this book.
Diane Ackerman, The Zookeeper's Wife - This is the true account of how a non-Jewish couple, who ran the Warsaw Zoo, used the zoo to hide Jewish fugitives during the war. What I find particularly humbling is that they had a beloved young son, who would have been brutally killed had their activities been discovered. How many of us would place our children's lives at such risk in order to help people of a different religion?
May there be no more such suffering - and may the Jewish People's right and reign over their homeland be uncontested.