For the vision, I think keith Cowan is right but perhaps
hasn't fully expresed the point. Keith says that the vision
can't be anything new, that it has to express what
everybody alread y knows. The point thats he left out is
that they usually don't know that they know it until the
vision is articulated.
Much of what we know is experiential and tacit (e.g., how
to ride a bicycle or how to deal with our peers) rather
than explicit (e.g., algebra). In our work helping
organizationsl to change and learn, we find the tacit
dimension of their knowledge to be much more important
than the things they know explicitly.
A speech like MLKing's changes everything precisely
because it articulates what we sort of or subconsciously
knew but hadn't quite figured out for ourselves. In other
words, that same speech given too soon would fall dead
because people wouldn't be ready for it.
A good vision has many of the characteristics of a
religious symbol -- it speaks, often in murky ways, to the
best of our impulses and it helps surface our tacit
knowledge. And the place to read to understand this role
of vision is some of the sociology of religion (e.g.,
Luckman's Symbols In Society).
If we are to make progress in understanding vision, we
have to be careful to distinguish between vision anc core
values. Another distinction that I think is important is
Stafford Beer's notion of identity.