The rabbi instructed the man to find the one who had originally owned the money and give him half of the wealth he had accumulated. Once he did so, the man's nightmares ceased.
There exists another parable which teaches about this mitzvah in a more indirect manner. In this Talmudic story (Ta'anit 25a) men carrying two measures of barley visited Rabbi Pinchas ben Yair. They deposited the barley with him and seemed to forget about it. Seven years later, the men returned to find that Rabbi Pinchas had sowed the barley and reaped great harvests. When he saw them, Rabbi Pinchas told them, without hesitation "take everything from your storehouses filled with grain." For Rabbi Pinchas, since the original grain had belonged to them, so too did all that was subsequently produced from that grain
In the first story, the man was unable to abide the fact that he had profited from the loss of another. He was then instructed not to return his entire fortune, but instead to share the wealth with the man to whom the money had originally belonged. In the second story, Rabbi Pinchas knew immediately what he was to do. Pinchas didn't simply share the wealth, but he handed all of the remaining grain (ie, the profits) back to the original owners.
Both stories operate based an underlying assumption that there is someone who is the "rightful" owner and someone else who is simply a "proxy" or "temporary" owner who must eventually relinquish not the original property, as well as all or part of what had accumulated. Both stories remind us that we must care for others as well as for ourselves. We have no right to profit from the misfortune, negligence or forgetfulness of others. Nor can we profit completely from that which is not completely ours. They also remind us that following these teachings is part of creating a caring society, just as much as the laws that protect the widow, the orphan, the poor and the stranger that we also find in this week's parashah.
We spend so much of our lives focusing on acquiring things, whether money, property, books, music, etc., etc. that we often forget to enjoy what and who is in front of us at any given moment. In both of the stories above, there was an assumption that something belonged to someone and therefore needed to be returned. Yet, there was also an assumption that nothing truly belonged to anyone, or else neither of the "finders" would have dared to profit at all or to keep or return - any of what they had amass.
These two stories bring to light an essential paradox in life with which we must struggle that I believe is also highlighted by the loss experienced by the victims and survivors of great tragedies. Given the nature of society as it has developed we must realistically focus on "ownership" and yet if we look at the grand scheme of things we really don't own anything. Those who choose to become monastic or practice a life of true simplicity give up everything except what they need to keep themselves warm and fed. Most people are not willing to do that, nor is that what I am proposing. For we are also commanded to rejoice in God's world and everything in it.
May we experience this Shabbat and every day as the series of moments in time, which they are. May we be mindful of and experience all the joy that each moment has to offer. May we remember to be grateful for everything and everyone with whom we share each particular moment. And may we do so acknowledging that nothing and no one can ever truly belong to us, nor can anything or anyone be permanent and eternal.