For more than forty years, the ancient mirror has been re-ground, and the moon is round. At the end of the moon, it is invaded by clouds. What does this sentence mean?

Say the first sentence first. The regrinding of ancient mirrors is a way to describe that the moon is round again. The ancient mirror represents the moon, and the re-grinding indicates that it is round and bright, which is generally used as Mid-Autumn Festival poetry. It is said that when the author was in his forties, he saw (the ancient well was grinded again, and the full moon was full), which meant that the generations were complete and the life was rich, but he did not expect that the full moon was overshadowed (covered by clouds) and suffered an accident. Only in my old age did I get lucky and live a very comfortable life. Early years, that is, early years, were limited by fate and failed to make a fortune. Even with good fame and fortune, it was only in middle-aged and elderly people that success was achieved. You can only be promoted after middle age, and it is better to move and change your name. Who gave this to you, my friend? Remember to give extra points. Ask again if you don't understand.