Core values are the organization’s essential and enduring tenets — a small set of timeless guiding principles that require no external justification; they have intrinsic value and importance to those inside the organization. “The core values embodied in our Credo might be a competitive advantage, but that is not why we have them. We have them because they define for us what we stand for, and we would hold them even if they became a competitive disadvantage in certain situations.” The key point is that an enduring great company decides for itself what values it holds to be core, largely independent of the current environment, competitive requirements, or management fads.

— Built to Last: Successful Habits of Visionary Companies by Jim Collins, Jerry I. Porras