Rabbi Baruch Shalom Ashlag pointed out that since many Tzaddikim mourned throughout the ages for Jerusalem and did not merit to see the Temple rebuilt, we need to understand this statement on an inner level.
The Zohar teaches us that the collective Soul, the indwelling presence of God within us, the Shechinah, is the Jerusalem within us; each one of us having a unique aspect of her.
Jerusalem is known by many names in the Bible, (Tanach). By considering the names of Jerusalem: “the city”, the “city of David”, “the epitome of beauty”, we can understand more of the role the soul should be taking in governing our thoughts, our words and our actions.
The fact that our soul does not occupy the central role in governing us that she should, is the cause of our mourning. However, from its name itself “Jerusalem” Rabbi Ashlag also teaches us the way to help reestablish its presence in our lives.