Which is quite important, n'est-ce pas?
Here's a great essay, the thesis of which has the ring of well-researched and long overdue truth about it. What ISIS really wants. And the answer seems to be: to live up to the rather demanding caliphatic responsibilities placed on it by its own interpretation of the Koran and associated fundamental doctrines.
Both illuminating and, notwithstanding the horror and the menace, in its own way rather encouraging (seeds of its own destruction-style). To understand is not to forgive, it's to forewarn. Hopefully in places where policy is maturely made.