Lets re-define testing

Why do we need Test Policy above test plan and strategy?
How to define:
Why do we test?
What are Test goals and values?
When does testing start, when it finishes?
When testing is good enough?
The Test Policy is the best place where such questions are answered and that this document builds foundations to the whole testing process on top of it. We nee those answers for our test strategies and test plans, or did we already keep the focus on technical delivery of testing activities and do not look on foundations as they are clear to every one?However even that questions sound simple, what are the true answers? Do we wall have a common understanding of the responses?