According to my friend Alex Traiman, Tisha B'Av is the day of potential. The spies in the desert had the potential to excite the Jewish people about the Land, to set the stage for a great rite of passage, to be the harbringers of Mashiach. Instead they went over to the dark side and deflated the hearts of their brethren, casting doubt on the ability of the Jews to inherit the Land. Our generation's job is to be a tikkun for the sins of the spies, to overcome fear and complacency and to take this great oppurtunity - that is, the opportunity of the State of Israel - with our bodies so that we will merit to say "Vetechezena Einenu" - 'Our eyes should see' the very real redemption of the Jewish people and the world.