As part of the description of the Choshen, the Torah teaches that “you shall place the Urim Vetumim within the Choshen.” According to Rashi, the Urim Vetumim was a Divine Name placed between the folds of the Choshen. According to the Rambam the Urim Vetumim were in the stones of the Choshen itself.
Through the Urim Vetumim, the leader of Bnei Yisroel would be able to inquire of Hashem about matters of national concern. The name Urim Vetumim alludes to the fact that their words were illuminated (Or) and their words were precise or complete (Tam).
Our sages explain that the letters from the names of the Tribes would light up to spell out the answer. The Kohen would need Divine insight to be able to arrange the letters to decipher their meaning. This miraculous communication did not continue in the Second Beis Hamikdash.
The wordחשן (Choshen) shares the same letters as נחש (snake), the representation of evil and negativity in the world. Both words also share the same Gematria as משיח – Moshiach.
Golus was brought about by our sins and what is apparent is the reality of the snake. The Geulah and Moshiach, represented in the form of a Gematria, is ever-present within the world, but hidden so that we do not see it.
Tisha B’av can be viewed in the same way. We see the snake, as we mourn for the destruction of the Temple and our exile. But hidden within, Tisha B’av is the birth of Moshiach and the beginnings of the preparations for the Third Beis Hamikdash. The same is true in our personal moments of darkness as well.
Like the Urim Vetumim, we need to decipher and decode our perceived reality to see its true nature. Whether we see נחש or חשן – the snake or the Divine Spirit - is in our control. If we open our eyes, with light and precision, we can see the reality of Moshiach.
May we merit the immediate coming of Moshiach and the return of the Urim Vetumim together with all of the priestly garments, in the Beis Hamikdash Hashlishi.
~ Based on Sefer Halikutim entry Choshen, Likutei Sichos vol 11, p 133