The answer is boring, but Barksdale Boy got it above. It is from a poem by the famous Li Bai 春夜宴桃李園序, and the four well-known characters 浮生若夢 mean “Life is but a Dream... “ (to be continued?)
PS There is a 2018 mainland TV drama using these words in the title.
https://forums.soompi.com/en/topic/4...3509;梦/
It is also the Chinese title for a 1938 US movie
http://www.wikiwand.com/zh-tw/浮生若夢
You can’t take it with you