The fundamental distinguishing dynamic of enduring great companies is that they preserve a cherished core ideology while simultaneously stimulating progress and change in everything that is not part of the core ideology.

Put another way, the most enduring and successful corporations distinguish their timeless core values and enduring core purpose (which should never change) from their operating practices and business strategies (which should be changing constantly in response to a changing world).

In truly great companies, change is a constant, but not the only constant. They understand the difference between what should never change and what should be open for change, between what is truly sacred and what is not. And by being clear about what should never change, they are better able to stimulate change and progress in everything else.