Interesting article explaining this consolation:
http://www.israelnationalnews.com/Articles/Article.aspx/8401
Can We Conquer Death?
Kislev 3, 5769, 30 November 08 09:18
by Rabbi Aron Moss
(IsraelNN.com) Question
Rabbi, I just wanted to thank you again for your support to our family after the loss of my grandmother. You helped ease the pain of what was a very sad period.
One question I had is about the traditional words of consolation said to mourners: "May G-d comfort you together with the mourners of Zion and Jerusalem."
What exactly is the consolation in those words? How does comparing the loss of a loved one to the destruction of Jerusalem by the Romans two thousand years ago make me feel any better?
Answer
There are several parallels between the fall of Jerusalem and the passing of a soul. By contemplating these similarities, the mourners can find a profound message of hope in the midst of sorrow.
Although the destruction of Jerusalem primarily affected those who actually lived there, nevertheless it was a national tragedy. All Jews, including those who lived far from Jerusalem, were deeply pained at the loss of their sanctuary. The mourning stretched far beyond the city limits of Jerusalem. And this gave strength and courage to the Jerusalemites, knowing that the entire Jewish people was together with them, feeling their pain.
So too, although it is the family that is mourning for their loss, the entire community shares in their sorrow at the passing of one of our own. This is comfort in knowing that your sorrow is being shared by your people. You're not alone.
It's been almost two thousand years since the destruction and we still mourn for the loss of Jerusalem. But the Jewish people has never lost hope that the Temple in Jerusalem will one day be rebuilt. We cry for the loss, but we remain hopeful that very soon what we have lost will be returned to us.
In a similar way, we mourn the loss of our loved ones, but we have faith that we will one day be reunited with them. Our prophets have promised that the dead will come back to life when the Messiah comes and we will all meet again. This is comfort in knowing that the separation, as painful as it is, is only temporary. It isn't forever.
But it goes even deeper. While the Romans were able to destroy the buildings of Jerusalem, they could never destroy its spirit and inner holiness. No enemy can destroy the soul of Jerusalem; even today it remains the Holy City.
So too, death can only take away the body, the physical persona. But the soul lives on. Even after their passing, our loved ones are with us in spirit. They give us strength when we face challenges and they smile with us when we celebrate. While we can no longer see them, we can sense their presence. This is comfort in knowing that we are never really apart. They're still with us.
None of this denies the pain and sorrow of death. But it may take the edge off that pain to know that, like Jerusalem, the soul has eternal powers that even death can't conquer.
May we soon see the rebuilding of the Temple in Jerusalem, together with all those holy souls on high, reunited at last.