@mnl The idea is that our language is based on really concrete ideas -- our bodies, how they move, the space around us, etc -- used as metaphors to communicate more abstract ideas, which are then used to make more, eventually filling out an entire language.
The book I read was "Metaphors We Live By" by Lakoff and Johnson. (I had used some of Lakoff's textbooks in university linguistics). I think the book made its argument very well, but it was very dry to read. (Interesting, but not fun)