Sounds like strange advice. Let me explain.
According to Rabbi Solovetichik there are two kinds of Teshuva (return). One type of Teshuva calls for a complete obliteration of the past. “Certain situations leave no choice but the annihilation of evil and for completely uprooting it. If one takes pity and lets evil remain, one inexorably pays at a later date an awesome price…Repentance of the individual can also be the kind that requires a clean break, with all of man’s sins and evil deeds falling away into an abyss, fulfilling the prophecy, “An thou will cast all their sins into the depths of the sea” (Micah 7:19). Not only are the sins cast into the depths of the sea, but, also, all the years of sin – ten or twenty or even thirty years of the sinner’s life. It is impossible to sift out only the sins and leave the years intact.
Many have experienced this feeling or the desire to erase parts of our life. We feel nothing good can come out of those particular experiences or memories. We blot out the memory completely. We may be so successful at this that we really cannot remember the event even if asked about it or reminded of it. This type of Teshuva is useful and neccesary in certain situations.
There is another type of Teshuva. Says Rabbi Soloveitchik: “…there is another way – not by annihilating evil but by rectifying and elevating it. This repentance does not entail making a clean break with the past or obliterating memories. It allows man, at one and the same time, to continue to identify with the past and still to return to God in repentance.”
On one level, this is very simple to understand as a person who sins is able to redirect the passion to sin in a positive direction. Sinning actually uncovers spiritual forces within a person. A repentant person has the ability to sanctify those forces and use them for good. Again, in Rabbi Soloveitchik’s words: “…I am not a different person, I am not starting anew; I am continuing onward, I am sanctifying evil and raising it to new heights.”
There is a more radical understanding of this idea. In Halachik man Rabbi Soloveitchik talks about a “living past”. Psychologically, the past can be kept alive and changed.
Rabbi Chaim Navon, in his book Ne’echaz B’Svach, offers an analogy of two people who were in a car accident. One of them may decide never to get back on the road, while the other becomes a driving teacher in order to rain a new generation of careful drivers. They had the same experience – but the affect of that experience differed greatly between them.
The person who swore off driving had a dead past – a past that set up the future.
The person who became a driving instructor has a live past – a past that is defined by the future. This person’s past is defined by decisions of the present.
Living a life of dead pasts is depressing as we look back on life and see it littered with mistakes, troubles and regret. Such a life is a fleeting moment as the past is gone, the future has not yet arrived and the present is like the blink of an eye.” Such a life feels feeble as we cannot get a grip on time.
A life with a “living past” is uplifting and exhilarating and allows us to control time – all of time. Such a life recognizes the inner strength of a person to redirect their life. Such a life empowers us with the joy of knowing that God believes in our ability to sanctify past deeds. Such a life makes us masters over our entire life, not just what we do now or in the future, but what we have done in the past.
So, I come back to where I started. Do not let a goo sin go to waste. No one is perfect and we all make mistakes. The worst mistake of all is letting the past define our future instead of the other way around.