He marks this transition in the words פרה and אפר, the Parah, the Red Heiffer inspires us to Teshuvah, (symbolized by the ה) at which point we draw closer to HaShem's holiness, (symbolized by the א) and must acknowledge our own insignificance in the face of this, that we are like ashes, אפר. Just as we take the Red Heiffer and burn it into ash.
We see here two sort of contradictory images, one, we must learn to push with more and more effort, always seeking to grow and rise higher. At the same time, we must recognize our smallness and become like nothing.
This reminds me of a teaching of Rebbe Nachman that sometimes it seems as though our sins have returned to challenge us anew, even after we were sure we had overcome them. He explains that in fact these are new challenges clothed in the old clothes of previous challenges. So even as we climb sometimes it seems as if we have fallen.
Similarly he teaches (in yet another torah) that as we raise to newer levels we are pushed to the external aspect of newer and higher worlds which result in an apparent fall even though in truth we are always rising.
Likewise we find in the Pri Ha'aretz that the secret of ratz (running) and shav (returning) is that even the shav is actually an act of ratz.
What do we take away from all this? the only thing we really can: Pursue HaShem with everything you have and then pursue Him some more. The one catch that we learn here is, we have to keep putting in effort no matter whether we see any results (ever) because sometimes what looks like a backslide is just an invitation from HaShem for us to take another step closer.
If we want a good analog, perhaps we can look to relationships, we dread being in a conflict in our personal relationships, but when it happens and we successfully prove our love and devotion despite the temporary obstacles, the relationship is richer and closer than it was before.
Sometimes, when I'm particulary low, I rest my burden on Rebbe Nachman or the Baal Shem Tov, relying on them that everything that happened was meant to, and I only need to worry about moving forward, not cleaning up the messes I've made until now. Then, later, if and when I have renewed strength, I return to the massive task of cleaning up my act.
From here I can learn something even stronger, instead of just ignoring the mess, I now have a tool to use the mess to strengthen my resolve. This Torah basically teaches us that when things look bad, we can turn it on its head and see it as a sign that HaShem wants us all the more. Which can be a real comfort if we've learned to suspend that part of ourselves that always likes to raise doubts. (by the way that part of ourselves is the Amalek we are commanded to erase. ספק (doubt) = gematria 240 = עמלק)