One important aspect of grasping agile in my mind is to accept the fact that you cannot predict the unpredictable. Instead of making detailed plans to support the illusion that you know what is going to happen, you say “I don’t know”, but then let that knowledge, that you actually do not know be the base for how you approach your work.
http://marcus.ahnve.net/2007/06/22/steve-jobs-and-agile/