The Torah portion of Devarim is always read before the fast of Tisha B'Av, the day on which we commemorate the destruction of both Holy Temples. More importantly, it is a day when we focus on building from those ruins, seeing that exile is not in itself an end, but rather a phase in the progress of mankind to its ultimate goal - the Future Redemption.
Our Sages describe exile with the analogy of sowing seeds. Before a seed can grow into a flowering plant, its exterior husk must utterly decompose. Similarly, for the G-dly core of the Jewish people to flourish, all the external dimensions of their personality must be stripped away.
In the analogue, the descent that characterizes the exile wears away at our connection with G-d. Without gentleness or mercy, exile tears apart the husky shells of our personalities. Layer after layer of who we think we are, and what we've been trained to be, what we would like to be, is peeled away.
Ultimately, what is left? The very essence of the soul, the point within our being that is an actual part of G-d. And when that essence is tapped, true growth begins. When this pattern spreads, the Jewish people blossom. In doing so, they spread the awareness of G-dliness throughout the world, precipitating the dawning of the era of the Redemption.
Based on the Rebbe's talks, From Keeping In Touch published by Sichos in English
