[He inclines his head, visibly impressed. Skulduggery doesn't know very much about physics in general, but he knows enough to understand what Tony is talking about - particularly since sorcerers have become more and more interested lately in trying to answer those very same questions.]

True. There's a very good chance the sort of magic I use has a firm basis in what we know about the natural world. [He clicks his fingers to summon a flame into his palm.] Magic provides the energy, but I can't do this from nothing. I need heat, or a spark.