The law of karma, in the world of values, can be compared to the law of cause and effect that operates in the physical world. If there were no law of cause and effect in the physical world, there would be chaos; and people would not know what to expect. In the same way, if there were no law of karma in the world of values, there would be an utter uncertainty of the results that people cherish; and they would not know whether to expect good or bad from their actions. In the world of physical events there is a law of conservation of energy, according to which no energy is ever lost. In the world of values there is a law that once karma comes into existence, it does not mysteriously flitter away without leading to its natural results but persists until it bears its own fruit or is undone through counteracting karma. Good actions lead to good results, and bad actions lead to bad results.
-Discourses 7th Ed., p332