The Three Weeks is the most mournful time of the year for us. The closer we get to the Ninth of Av, the more these mourning restrictions intensify. So what is the purpose of our mourning during this time? Our Sages teach us that the purpose if to stir us to t’shuva, repentance.
Rabbi Natan teaches us:
The essence of the destruction of the Beit HaMikdash, the Temple, came about through blemished judgment, as it states, “You who turn judgment to wormwood” (Amos 5:7). Not only did the generation of the Destruction fail to do justice, they damaged [the attribute of] justice, thereby enabling Nevuchadnetzar to gain control over that attribute.
T’shuva, repentance, comes about through justice. When a person practices hitbodedut, person prayer, and scrutinizes one’s deeds, judging oneself and arousing oneself to return to Hashem, one avoids having to be judged … because “When there is judgment below, there is no judgment Above, in Heaven” (Midrash Tanchuma, Mishpatim 5)…
The Destruction [of the Temple] came about through blemished judgment. Therefore, we must now do t’shuva and rectify this by judging ourselves, and fasting and refraining from pleasurable activities, in order to annul the judgment on High…
The most important aspect of mourning is to reflect on one’s own actions, and to understand that they were the cause of the Destruction. As it states, “Any generation in which the Beit HaMikdash is not rebuilt is considered as if they had destroyed it” (Yerushalmi, Yoma, 1:1). We must mourn our own sins and cry over them very much, and do a thorough soul-searching. In this way, we will merit the building of the Beit HaMikdash, for “Whoever mourns over Yerushalayim will also merit to see its rejoicing” (Taanit 30).
Likutei Halakhot, Ko’ach v’Harsha’ah 3:6-9
Each of us, according to our sins, has a share in the destruction of the Beit HaMikdash, the Temple. However, rather than throwing us into despair, we must realize that we can correct this. As Rebbe Nachman says, “If you believe breaking is possible, believe fixing is possible” (Likutei Moharan II: 112). Each of us, according to how we judge ourselves and merit to correct our deeds, has a share in the future rebuilding of the Beit HaMikdash, speedily in our days, through the rectification of the misdeeds of each of us!
Based on Likutei Halakhot and Beyond Time, by Erez Moshe Doron, The Three Weeks