Literally: summer – furnace – winter – fan
Alternately: Useless things. Things inappropriate to the situation, including skills, ideas, or opinions. Sources of warmth in the summer, sources of cooling in the winter, or perhaps pathological narcissists in a democratic government.
Notes: 炉 may be written as 鑪 (an alternate form of the same character) without any change in meaning or pronunciation, although this version is rare. And while the character 炉 on its own means “hearth” or “furnace,” in this context it refers specifically to heating devices, such as braziers of hot coals, rather than to a fire being used for work.
This compound is attributed to the Lunheng, a collection of essays from the Eastern Han dynasty in the first century CE.