This Shabbos represents the resiliency of the Jewish nation. Six days ago, we sat on the floor as mourners, engulfed by despondency and despair, and today enveloped in an atmosphere of optimism. The excitement comes not only from the parsha of Vaeschanan with its many basic mitzvos of talmud Torah, tefillin, mezuzah, and the Aseres Hadibros, as well as the prohibition against intermarriage. The optimism is not only from the haftorah where the navi Yeshaya promises us that as we were persecuted most severely, so will we be comforted. The additional optimism comes from today being Tu b'Av, the fifteenth day of the month of Av. The Talmud at the end of Taanis and Bava Basra (125a-125b) enumerates six phenomena that occurred on this day that make its significance and joy comparable to that of Yom Kippur.
The last factor contributing to the uniqueness of this day is that it marked the culmination of bringing the wood for the fire on the mizbeach. The Torah (Vayikra 6:6) legislates that there is to be an aish tamid - a perpetual fire ablaze on the altar. The Talmud (Yuma 21b) informs us that in actuality there were three fires on the mizbeach: The largest one was to consume the meat sacrifices, the second largest fire was to provide the coals with which to light and offer the incense on the golden altar in the heichal, and the third one was to fulfill the Divine directive of having the perpetual fire that should not be extinguished.
There is a recurring metaphysical theme throughout many of the mitzvos according to the understanding of the Sefer HaChinuch. His basic thesis is that chesed to one's fellow man and giving to Hashem is in reality a boomerang and ultimately benefits the donor. Allow me to explain. Man, by his very nature, is limited both materialistically and spiritually. His actions are therefore limited as well. The concept of a bracha is to break through the limits of man's actions by giving and attributing a portion to Hashem, which then limitless just like its Master is, thereby allowing bracha to settle on its object and expand limitlessly. Thus, when the Jewish nation provides the lechem hapanim weekly, fulfilling, "on the Table shall you place show-bread before Me always" (Shemos 25:30), our giving and offering Him bread allows Him to bless our bread and sustenance (see Chinuch, mitzvah 97.)
Interestingly, the Chinuch (mitzvah 132), explaining the significance of our kindling a fire on the altar even though in the time of the first Beis HaMikdash fire miraculously descended from Heaven, says that man is comprised of four elements: dust, water, wind, and fire. The wood cut between Nisan and Tu b'Av is dried by the intense heat of the sun, preventing the wood from becoming wormy and thus providing the best flammable material. Once the wood has been severed, it goes from tzomeach - that which grows, to domeim - a lifeless object, and as Hashem accepts this wood and allows it to fuel the mizbeach, He then takes our domeim - lifeless element, the dust within us, and lights our fire. As the burning fire on the altar is beautiful to see and practical, so too does He take our personal fire, our drive for life, and calibrates it. Too much fire in man will consume him, anger him constantly and will not allow him to interact patiently and harmoniously with others. Too little fire will leave man without principles, without determination, a wimp. Thus our hiddur mitzvah which is accomplished by finishing this mitzvah by Tu b'Av to ensure the highest quality wood, gains us His blessings in return.
There is a moving Yalkut Shimoni at the very end of V'zos Habracha that describes Moshe leaving the mitzvah of bizuy Mitzrayim (gathering the wealth of Egypt), and for three days and three nights searching for the bones of Yosef. Pharaoh's advisors told him that if he doesn't want the Israelites to leave he should hide the bones of Yosef since they pledged not to leave without his remains, and they will surely be loyal to their pledge! Exhausted, Moshe meets Serach the daughter of Asher. Seeing Moshe totally fatigued and inquiring why, she then takes him to the shores of the Nile, where Yosef had been buried deep in the waters in a heavy casket to ensure that the Jewish nation would not leave. The rest is history. Moshe prays and Hashem delivers, but only after Moshe extends his greatest effort in this project. The lesson is clear: we have to put in our maximum effort and He will respond in kind.
In the Nachem prayer we recited on Tisha b'Av we conclude, "for You, Hashem, consumed her, and with fire You will rebuild her." I'd like to suggest that since we, the Jewish nation, took the Beis HaMikdash for granted and did not bring our fire/enthusiasm to the Beis Hamikdash, it became a lifeless shell lacking the soul and fire of the Jewish people, and therefore it was consumed with natural fire. We pray that in the near future, in the merit of our studying and appreciating the korban eitzim (the wood donations) and our pining and longing to fulfill this mitzvah as well as all other mitzvos related to the Beis HaMikdash, this fire and enthusiasm will speedily cause the rebuilding of the third Beis HaMikdash in our days.