What painting has been the most influential for you, (meaning that you feel personally and emotionally connected to it in some way, not just for aesthetic reasons)?
Probably René Magritte's "Le maitre d'ecole" (http://pintura.aut.org/SearchProducto?Produnum=28651).
My mom used to give me a Magritte book when I was 2 or 3 years old to distract me, and this painting was in the cover. It fascinated me, and still does.
