All sentient beings will grow old and wither. Don't look at the sunrise and the moon in the sky. The situation is always new and never changes. If it has feelings, it will still age. The sentence "If there is love in the sky, it will grow old" should be absurd, which Sima Guang called "absurd". It effectively sets off the difficult situation and bitter feelings of the golden bronze immortal (actually the author himself), with a broad artistic conception and deep feelings, which is a famous sentence throughout the ages.