Talking about the cycle of the four seasons

The next sentence is about the change of the world. What he means is that the four seasons change all the way, that is, the four seasons change in spring, summer, autumn and winter, and the sea changes into fields and fields into the sea. It is a metaphor that the world is changing very quickly, and everything is ever-changing, not static. Therefore, our thoughts should keep up with the trend of the times and keep moving forward.