All dharmas are impermanent

All dharmas are impermanent, and emotions are also impermanent; all pass through the stages of arising, abiding, changing, and ceasing. Whether good or bad, none can endure unchanged or last forever. If the emotions of joy, anger, sorrow, and happiness arising from the afflictions of greed, hatred, and delusion could persist forever without change, imagine what would become of sentient beings? The result would be mental breakdown and ultimately death. Even if a mind of joy and delight without the nature of affliction were to remain permanently unchanged, such a person still could not attain profound meditative concentration (samādhi).

The worldly law of impermanence is what suits the survival of sentient beings. If a dharma were to become permanent, sentient beings could not bear it. Although impermanent dharmas cause sentient beings suffering, permanent dharmas would likewise cause suffering. This is why the world is suffering.