Geometry... via re-ality
Mr. Pei's words aren't just true for architecture, they're also true for building lasting brands. For a brand to stand the tests of time, it has to have roots that help it stay true over time. Why? Because lasting relationships are built on a foundation of trust. If you are constantly changing who you are and/or what you stand for, how can anyone come to trust you?
In relation to this, if you are working on a brand that has lost its way, it's often very helpful to go back into the history of the company and find what they stood for when they first started. There are likely some great things there that can be polished up and brought to life in an appropriate way for today's culture.
As the economy contiunes to struggle and technology brings us more new ways to communicate with people, it will become more and more tempting to chase things that take us away from our roots. We have to do everything we can to not let that happen. It's important to always look at the core principles - the roots - of your brand to help guide the way.