Cemetary of Dead Metaphors

Mad as a hatter - trans. someone who demonstrates insane behaviour. Was once a reference to erradic behaviour in hat makers caused by mercury poisoning from the mercury-treated felt

Rule of thumb - trans. general precept. Originated from legislation saying a man was able to beat his wife with anything thinner than his thumb

Bated breath - trans. suspensful anticipation. Origin unknown

Pregnant pause - trans. a gap in conversation that is filled with meaning. Origin in biological sense of pregnancy and now a fully fledged metaphor all on its own

On the same page - to share an understanding or method of thought. Origin from book sharing in monasteries

Turn of phrase - I have no idea with this one. It sounds like something just born into metaphor.