I look for material that both interest me and challenges me. If I am drawn to the material and I have to work hard at it, the characters and the plots reflect the hours and hours of research.
“Peter was 2 years and 10 months old when we began to study him. He was afraid of a white rat, and this fear extended to a rabbit, a fur coat, a feather, cotton wool, etc., but not to wooden blocks and similar toys.”