“A dog returns to its vomit”: In biblical times, people did not see dogs as friendly family animals. They saw them as wild and unclean.
“A sow that is washed goes back to her wallowing in the mud”: This saying may come from a well-known book of wisdom called Ahiqar from around 500 BC. One version says, “My son, you have been to me like the pig who went into the hot bath with people of quality, and when it came out of the hot bath, it saw a filthy hole and went down and wallowed in it” (Ahiqar 8:18).