I waxed philosophical over this a bit (I blame it on Silk Road's Introspection ceylon tea!) noting to myself that I had to have the black for the white to show up so starkly. There's no light without the shadows.
I did this in my Book, smearing black gesso all over the pages first (which, by the way, stinks like the devil's own jock strap... seriously horrid), letting it dry and then drawing the bones with my favourite pencils of all time: the set of EVERY PRISMACOLOR EVER MADE that my always-fabulous mother-in-law gave me last year for Christmas.
Ever notice how cats make philosophy look either totally pretentious or too deep for humans to understand?