I'm in London, having just finished presenting at QCon.
One of the tracks was called Reflecting on our Agile Journey - How do we reach Mastery? The more I think about that, the more the title worries me, because it seems to contain an implicit assumption—that mastery is some state that can be reached.
I think there are methodologies which can be mastered, where you can say “now I know it all.” I don't believe agility is in that camp. For me, agility is all about the journey. Along the way, we'll always be faced with forks in the road. The agile principles help us decide which to take. And we just carry on, enjoying the trip and doing our best along the way.