I'm wondering if anyone could explain to me a little more of the theory behind a sacrifice of some sort (not necessarily living, mind you) powering or empowering a working. I've encountered the concept a lot, but sacrifice as I understood it involved giving something to (the) god(s); can its energy be harnessed? Indeed, is there energy to harness?

Any and all thoughts welcome. (IMG:style_emoticons/default/smile.gif)