The Universal Law of Harmony
This law supersedes even the fundamental law of Karma, for harmony is the supreme potential of balance.
The purpose of Karma is to attain harmony.
If you throw a rock into a pond you disturb the harmony of the pond, you are the cause, the effect is the splash and the ripples that flows out and back until harmony is restored.
Similarly, your disharmonious actions flow out into the Universe and back upon you, lifetime after life time, until eventually your own harmony is restored.