Wow, pretty cool comparison about the bears.. :)
Try writing a paragraph about any insight that comes to mind -- for example, you can write that the satisfaction that seems available in revenge is actually an illusory kind, and that no real satisfaction can come of it. In this paragraph, include a quote or example from the play.
Next, write another para that explains the thesis in a different way.
After repeating that process several times, go back and create an introduction. Don't try to introduce something that does not yet exist. Don't write the intro first.