If, for example, you lose money in a public thoroughfare, since there is no way to identify the Owner through the money lost, then whoever finds it, keeps it. There is a general assumption that in such cases the owner gives up hope of getting it back. And if we look at our generation we can see the parallel between lost Jews and lost olives. Now matter how deeply encrusted the surface may be from a life devoid of spiritual light, the essential characteristics can still be discerned. And this is why the eternal light in the sanctuary is lit from olives, indicating that though the Jew may be lost today, the potential light is there for all time.
Every case is unique, special, utterly individual.
Many touch on the tragic side of life, but one case which springs to mind, in retrospect, was quite humorous. One night after a Wednesday night lecture, a man approached me and asked if there would be a minyan for maariv since he needed to say kaddish. I directed him to the Bet Midrash upstairs where a minyan would be starting in a few moments. The man didn't look familiar, and I didn't pay any more attention to him. During the service I noticed that he had some difficulty with the Hebrew, but when it came to kaddish he was quite fluent, indicating to me that he must have had some background, but during the years had drifted off, letting his tongue get a bit rusty when it came to the Hebrew.