Pen & Ink plus dyes. Having not worked with dyes in quite a spell, I got a lil' dark in my 'aged paper' effect. My inks seem a little thicker as well, but overall, at least it doesn't look more like a Grandma Moses.
Tidbit of information- Mr. Geisel, as his friends call 'im, was a devout Lutheran. I thought he was Jewish. Oh well- at least he liked Jewish people. Unlike Luther... who so happened to be the father of Lutheranism. But Seuss wasn't too fond of the Japanese. Until after the war... then he felt bad for what he said about them during WWII, and made up for it.