How do I compare Lear (Edward Bond) and Shakespeare's King Lear with regard to their treatments of sanity and insanity?
I haven't read Bond's version, but the best thing to do is to take both characters and make a list of things that are similar and dissimilar about the two. Don't think too much about it, just start listing things about one and then do the same for the other. After you have about ten or so items for each character, take a look at what you've got...do you see any patterns? Then rewrite your list or make a chart to more clearly see these patterns. Start with age, physical description, family members, personality, motives for things they each do in their respective works, political stance, personal preferences for things, friends, mental health, etc.
I have included a link to help you focus on how to compare and contrast with regard to your focal points...sanity and insanity, for instance. There are also links to character analysis from each work.