The idea behind this article (linked above) is that the purpose of a company (or organization) should not just be for that organization, but with its customers (non-members). As an Alpha Gam, the Purpose I strive to live by holds me to a certain standard publicly - that Purpose is not just about me, or the sorority of which I am a member, but how I interact with the world around me. When I truly live by that Purpose, it should be inevitable that others would come to be familiar with it.
Whatever your own purpose is (as an individual, part of a company, or organization) - how does it lead you to interact with your community? How do you share your purpose?