文章合为时而著，歌诗合为事而作。
Serious translation: Prose is written for the era, poetry is written for the moment.
New Living Internet translation: Post takes as long as the world needs to hear them, post memes while they're still funny.
source: https://zh.wikisource.org/zh-hans/%E8%88%87%E5%85%83%E4%B9%9D%E6%9B%B8