To me, the only one true principle of Agile is to: - Always take time to reflect on the way you and your team work - Discuss openly if it's appropriate or not - Be ready to accept ANY solution that is discussed, be it organizational, technical, or self-improvement.
I would even go as far as calling it a basic principle of engineering. It is very simple to state, but very hard to implement due to our human nature (ego and feelings get in the way of open discussion and self-change) and budgets (taking time to discuss and implement change feels like a cost to most management, not added value).
There were examples of this principle and mindset in many organizations long before Agile was codified, and it can actually cause valuable results in organizations that look nothing like the stereotype of Agile !
For example, the NASA software department was famous for stopping all developments any time their QA detected any bug, and taking the time needed to ensure this kind of bug can never be committed again in the future. This kind of behavior is extremely Agile to me : continually improving your process to match your requirements. It is very slow and expensive for them, but it matches the stakes (potential loss of lives).
I think true Agile and agile organization are big foot that common people like me have never seen. Only enlightened Agilist understand the meaning of:
Agile is Nothing, Nothing is Agile. If scrum is not enough have scrum of scrums if scrum of scrum is not enough have scrum of scrum of scrums (duh).