When you’re afraid of a disaster, don’t just sit still, that’s all I’m saying.
Literally: rapid – wind – swift – thunder
Alternately: High winds and a violent thunderstorm. By extension, any situation that develops rapidly or changes violently.
Notes: Replacing 迅 with homophone 甚 (“exceedingly”) or 雷 with homophone 来 (“to come”) is an error.
This compound comes to us from the Book of Rites (礼記, in Japanese Raiki), a collection of disparate writings that eventually became one of the foundational texts of Confucianism.