I found the following rather old, yet interesting, post over at the blog: Note x Note: Musical Musings & Cultural Observations.In essence, it is a very concise and lucid attempt to explain Wagner's use of the leitmotif and the manner these were then used by Hollywood film composers - a topic discussed here on a number of occasions.
As the author puts it:
"A rather compelling case is made for the idea that Wagner's leitmotifs are the precursor to modern film scoring which often utilises musical representations of various characters, places, and objects"
Well worth a visit. To read more and watch the video please visit: "Let there be Leitmotifs!