Have you ever thought about the origin of some of the sayings in your everyday vocabulary? Most people use these phrases without thinking why they mean certain things. Language is changing over time due to linguistic and extralinguistic factors and, in time, the true meaning of phrases can be forgotten, changed or simply taken for granted as a cliché.
Can you imagine a real rain of cats and dogs? Or, perhaps, a cat getting your tongue? If you wonder why some strange English phrases are used as they are, you are in for amazing discoveries.