Meaning
Reciprocity is a structural law of physics and spirit, not just a moral suggestion.
Usage Context
Used to warn a wrongdoer that their power is temporary or to encourage a patient person that their good deeds are coming home.

Life is not a linear line but a 'circle.' An act of greed or an act of kindness travels away from the individual into the world, but the geometry of the universe ensures that it must eventually return 'past the starting point' (the person who initiated it). It teaches that you cannot escape the consequences of your behavior by moving; the cycle will eventually catch up to your current position.
Reciprocity is a structural law of physics and spirit, not just a moral suggestion.
Used to warn a wrongdoer that their power is temporary or to encourage a patient person that their good deeds are coming home.
What goes around the circle must eventually pass the starting point. The law of inevitable return. Your history is always moving toward your future.