Some have theorised that the universe is but one manifestation of existence, and that there are an infinity of other universes, inaccessible to the normal principles of science, but nonetheless present in the minds of the inspired few special people.

If this were the case, then it could be theorised that there are lines of energy running between these many different universes, and it could be again theorised that if there are lines of energy running everywhere, perhaps that energy can be tapped for magical uses?

Well - yes it can. Exceedingly powerful effects can indeed be generated by tapping into ley-lines. The only problem is - not everyone can detect and use ley-lines. In fact - its a pretty select group that can - and not a very popular group either, in the great multiversal scheme of things.

Demons. There - I said it. Ley magic is Demon magic. Sorry folks - there's no nice way to gloss over that one.

What - you mean you can see ley-lines?

Oops.

Perhaps your someone hasn't been completely honest with you about your origins...