Something that happened almost two thousand years ago comes back to haunt our collective consciousness as if it happened yesterday.
This is what so impressed the French ruler Napoleon Bonaparte when he looked in on a synagogue in Paris on Tisha B'Av and saw Jews sitting on the floor chanting lamentations and shedding tears. After inquiring about the cause for their mourning and hearing that it was the destruction of their Holy Temple in Jerusalem he expressed astonishment that he had heard nothing about this tragedy from his reliable intelligence sources. When it was explained that this event took place close to 1800 years earlier he reportedly declared that a people who can still mourn for their Temple and their homeland after so many years have a real hope for regaining them.
Napolean distinguished something unique about the long memory of the Jewish people but could not truly understand its meaning.
A Jew mourns the fall of Jerusalem, the destruction of the Holy Temple and the two thousand year exile that followed not out of a sense of nostalgia for the glory and prosperity of bygone days. For a Jew loyal to his conviction that he is the proud member of "a nation of priests and a holy people" who were chosen to receive the Torah at Sinai and to serve as "a light unto the nations" there is much more involved in remembering the past.