I like spending time in antiquarian bookstores. I seldom find what I am looking for, which is exactly the point. Finding what you didn't know you wanted or needed is more fun. It adds something to the work, whether I'm writing or illustrating. I think it's called "cross-bred vigor." Uniformity is boring. So, I wasn't looking for it but I found a book filled with Renaissance and Baroque imagery: moons, suns, heaven, hell, planetary machinery, angels and demons, a catalog of supernatural rigamarole. I'd forgotten how to crosshatch, but it was fun relearning it. Dead masters can teach you a lot.