It has nothing to do with modeling the mind after steam machines. These expressions exist because of beliefs about how the mind works, not the other way around.

It has nothing to do with modeling the mind after steam machines. These expressions exist because of beliefs about how the mind works, not the other way around. Feelings would still get "bottled up" and you'd have to "release" them somehow, even without knowledge of steam machines. Yes, it's the Sapir-Whorf hypothesis all over again.