Fire is a good servant but a bad master

Proverbial Meaning: Fire is very useful when it is under one's control, but very dangerous when it is not.

Literal Origins: Servants usually do what you tell them, where masters tell you what to do, so fire makes a better servant because no one would want a master that could burn you.

Common Usage: The idea of masters and servants is very old-fashioned now, so it is very unlikely that most English people would use this proverb, unless they happen to be aristocrats with servants.