Shabbat Nachamu. What is the nechama for us if we are still in golus? The Gemarah (Taanis 30b) says כל המתאבל על ירושלים זוכה ורואה בשמחתה, "whoever mourns for Jerusalem will merit and see her joy." What does the Gemarah mean, there were many great tzaddikim who died without seeing the rebuilding of Yerushalayim? The Sfas Emes (Shemos 5763) notes that Chazal do not say in future tense, יזכה ויראה, one will merit and see, rather in the present tense, זוכה ורואה, one merits to see now, in the golus, he joy of Yerushalayim. How can one see the joy of Yerushalayim if we are still in golus?
The Baal Shem Tov teaches (see Baal Shem Tov on the Torah Noach #31) that a person is where their thoughts are. In other words, a person is not defined by where they are physically but rather where they are mentally. Says the Kedushat Levi, one who properly mourns over Yerushalayim, one who's found in the ruins of Yerushalayim, will זוכה, from the word זכה, become purified, will become elevated to be able to experience a taste of its joy as well. Paradoxically, when one mourns for Yerushalayim, one becomes capable of seeing its glory.
How is this so? As the Yaavetz notes in his siddur, we say in benching ועל ירושלים עירך, ועל ציון משכן כבודך, ועל מלכות בית דוד משיחך, to have compassion on Yerushalayim, the Mikdash and malchus beis David. But they are long gone? Says the Yaavetz, that Yerushalayim and the Mikdash in the spiritual realm are still standing. When mourning the physical loss of Yerushalayim, one is given the proper eyes to see the spiritual structure of Yerushalayim. One is no longer trapped in the mindset of brokenness but is able to see the joy of geulah. As the Chassidic masters teach, golus and geulah are also states of mind. When one feels the pain of Yerushalayim, then one is elevated to be able to live in the mindset of its joy.
There is a story in the writings of the Arizal (cited by the Magen Avraham in shorthand 493:3) "Rav Avraham Halevi testified before me that he was accustomed to reciting Nachem daily in Shemoneh Esrei, lamenting the destruction of the Temple. One year on Lag BaOmer when he was by the Rashbi and included the above prayer in his Shemoneh Esrei, the Arizal approached him with a stern message from the Rashbi. “Rebbe Shimon came to me and told me to ask you why you chose to say Nachem on the day of his Simcha? Rebbe Shimon said that due to this you yourself will unfortunately experience a reason for condolence in the near future.” And so it was that in that month Rebbe Avraham’s eldest son passed away." What is wrong with someone who longs for the Mikdash so much that they say nachem daily to say nachem on Lag BaOmer? The Lubavitcher Rebbe explains that Rashbi lived on the level of רואה בשמחתה, he lived in a geulah mindset and hence on his day it is not appropriate to say nachem.
In the parsha we read וּבִקַּשְׁתֶּ֥ם מִשָּׁ֛ם אֶת ה אלקיך, "And from there you will seek the Lord your God." The Sfas Emes (5664) says it doesn't say seek the geulah, but in the golus itself you will seek Hashem, in the golus itself we can have the capability to come close to Hashem, to experience a taste of necham, a taste of the future.
That is the nechama. We may still be in golus but after going through the mourning period for the Mikdash, after becoming attached to the Mikdash we are able to be רואה בשמחתה, to have a sense of a little bit of the geulah mindset, to feel the sprouting of the geulah even as we are still in golus.