That saying is what we call an Idiom. There’s lots of them and, according to the Phrase Finder, this one dates back to the 1500′s. To me they represent common sense that has been passed down through the ages.
Idioms are on the differential diagnosis of FIGURATIVE LANGUAGE – literally! They also remind me of English classes at boarding school where grammar was metaphorically pounded into our heads.
I guess I am dating myself with ponderings on the evolution of grammar [and the English language for that matter] -or should I say devolution? People always tell me I that I speak English really well [for an immigrant from Kenya] … sadly my English has gotten worse since I moved here. I would never be caught dead saying things like “I got it“.
Here’s a great infographic on common grammatical mistakes that make you look silly.