Its more than a simple belief that there is good and that it should fight the evil in the world. It's a personification of Light and Darkness at their most elemental level, as forces that are so absorbed with themselves that one cannot exist without the other though they constantly try to consume one another. One of the earliest repersentations of Light and Darkness was of Light being a massive black bull and Darkness being an enormous white bull.
P. C. CastA big, studly football jock like me? I got plenty of blood to spare. For you, I have anything to spare.
P. C. CastThat don't look good," Kramisha said. "Not good at all." She paused and then her eyes went from me to Heath, whose attention was so focused on me I swear he didn't look like he would notice if a giant white elephant in a tutu danced around the room. "Ain't that the human kid who was down here before?
P. C. Cast