http://www.cuttingthroughthematrix.com/books.html
Alan Watt's books; 'Cutting through the Matrix' 1,2 & 3 explain the origin of a lot of our language. He's done a power of research.
I haven't read them yet, merely flicked through a friend's and was Fascinated!
{He's going to take a Long time to read & digest there's so much there, so ordering my own!}