The Book of Devarim begins with Moshe's reprimand of the Jewish people as he recalls the numerous places in the desert where they rebelled against God.  This is a way of reminding them, as they merit entering the Promised Land, not to be spiritually complacent.   

Rather than rebuke the Jews directly, Moshe softens his words by alluding to the locations where the rebellions took place, and does not mention them directly.  For example, Moshe uses the phrase "ve-di zahav," which is a place that does not actually exist. But, as Rashi states, the words mean "an abundance of gold," referring to the gold the Jews took from Egypt from which the idolatrous Golden Calf was made. (Deuteronomy 1:1)  This type of allusion is employed by Moshe so that each person be able to remember the tragedies in the desert in their own way.   

Not coincidentally, the portion of Devarim is always read on the Shabbat prior to Tisha B'Av, the day commemorating the destruction of the Temples in Jerusalem.  On this occasion, a different device is used to trigger memory.  

Rav Yosef Dov Soloveitchik, of blessed memory, called this period avelut yeshana, the mourning over an event that occurred long ago.   Some ritual mechanism was required to feel the intensity of this loss.  Thus, the halakha mandates that as we move closer to Tisha B'Av, the mourning process becomes more and more extreme.  

Hence, three weeks prior to Tisha B'Av, on Shivah Asar B'Tamuz, the day that the walls of Jerusalem were penetrated, we begin to mourn by restricting ourselves as we would when mourning during the year following a parent's death.  And almost two weeks later, on the first day of the month of Av, a nine day period begins.  This time is more restricted as we mourn the way we would during the first thirty days after a close relative's death.  Finally, on Tisha B'Av, the mourning becomes strongest as we sit on low chairs and follow other restrictions that are kept during the shivah, the seven days of mourning immediately after the death of a loved one.     

Note, how this process of mourning is the reverse of what Rav Soloveitchik calls avelut hadasha, recent mourning, the mourning after one has just experienced the loss of a close relative.  There, the movement of restriction is from the more to the less intense.  This, because the loss is often most powerfully felt when it occurs.  With time, the mourning ritual becomes less restrictive, allowing the bereaved to gradually return to the everyday world.  

The confluence of our portion with Tisha B'Av presents different conduits to remember the past.  Sometimes, the goal is to soften the recall as occurs in our portion; and sometimes the goal is to find a ritual mechanism to take events of thousands of years ago, and make them come alive in the present.

Shabbat Shalom,

Rabbi Avi Weiss