I'm currently fawning over Drawing Lessons From The Great Masters, especially the sections "Light and Planes" and "Mass". The idea of an artist throwing out the current lighting that he/she physically sees on the model and using their own light and shade based on knowledge of what they know with simple shapes, is totally awesome. There's a sense of control over drawing (instead of drawing controlling you)
I'd love to find a resource that shows shapes in different lighting scenarios for future study, yet have not been able to do so.
Any help on overcoming this hurdle?