In college, I took an etymology class. It was fascinating. The library had a set of encyclopedias in which a student could look up a word and read about its origin and how it’s meaning adapts over time. Fortunately, there is now a similar tool available online. Etymology Online
@ibstubro “Throwing the baby out with the bath water” started from a literal sense. Back in the days of yore when there wasn’t indoor plumbing and people didn’t bathe every day, a tub would be hand-filled with water. Family members would take turns bathing in the same water, starting with the eldest and working down through the family. By the time it was the baby’s turn, the water could be so filthy that if a baby slipped underwater, it might go unnoticed until emptying the tub.
It has evolved into its figurative meaning today: Don’t get rid of something valuable while discarding unwanted items or ideas.