I did not write the following poem. The author is a man much wiser than I could ever hope to be: Rabbi Harold Kushner. I suspect that the introductory paragraph is just that. Most sources begin the poem with "Each Lifetime ...."
There must have been a time when you entered a room and met someone and after a while you understood that unknown to either of you there was a reason you had met. You had changed the other and he had changed you. By some word or deed or just by your presence the errand had been completed. Then perhaps you were a little bewildered or humbled and grateful. And it was over.
Each lifetime is the pieces of a jigsaw puzzle.
For some there are more pieces.
For others the puzzle is more difficult to assemble.
Some seem to be born with a nearly completed puzzle.
And so it goes.
Souls going this way and that.
Trying to assemble the myriad parts.
But know this. No one has within themselves
All the pieces to their puzzle.
Like before the days when they used to seal
jigsaw puzzles in cellophane. Insuring that
All the pieces were there.
Many pieces to someone else's puzzle.
Sometimes they know it.
Sometimes they don't.
And when you present your piece
Which is worthless to you,
To another, whether you know it or not,
Whether they know it or not,
You are a messenger from the Most High
(Rabbi Harold Kushner 1977,Honey from the Rock, pp. 69-70).