Figuring Out Metaphors

John R. Searle actually help me figure out and and question metaphors.I understand how authors speak metaphorically and do not mean what they say literally. I didn't understand how I might assume that the author is speaking metaphorically, but it might be much harder to figure out what he means. I didn't know that the existence of such utterances pose a series of questions for any theory of language and communication. Such as: Why do some metaphors work and others do not?; Why do we use expressions metaphorically instead of saying exactly and literally what we mean?