Dark. Light. God. Lucifer. Heaven. Hell. GOOD. BAD. Yes, the Ever-lasting contrast. Since existence has known, the 'fight' between good & evil has continued. Obviously, this fight can never end. Good things turn bad, bad things become good.
My fav. contrasting symbol, because it is so true & means so much - the battle between good & bad never ends... The tragedy that is Dylan Klebold.