One theory of history holds that new ideas spring forth to different people in different locations at approximately the same time. (See the "Convergence of Sciences" link below for a fascinating look at some evidence for this.) Colloquially, we reflect this theory when we speak of an idea "whose time has come." This usually stands in opposition to the "great man" theory which holds, for example, that only Isaac Newton could have invented the Calculus when he did. Patently false, I know, but still some people do still believe that.All of this is preamble to the - some would say remarkable - similarity of the three tiered hierarchy I described a couple of weeks ago (Identity-Persona-Role) as the building blocks of an identity management system, to that described by PingID's Andre Durand in his essay "Three Tiers of Identity" from last winter. Note also that it was the Open Group's Ed Harrington who provided the structure for the hierarchy I described.Durand calls the three tiers Personal Identity, Corporate Identity, and Marketing Identity. He defines Personal Identity as "...both timeless & unconditional... your true personal digital identity ... owned and controlled entirely by you, for your sole benefit."The Corporate Identity, in his schema, is "...both conditional & temporarily assigned." Corporate Identities "... can be revoked either by us or the company that issued them."The third tier, Marketing Identity, he defines as an "...abstracted identity. For example, we're either a 'frequent buyer' or a 'one time customer' etc." Marketing Identities, in Andre's hierarchy, "are typically based upon our demographics or our behavior in our interactions with business."I think it's very easy to map Durand's Personal, Corporate and Marketing onto the Identity, Persona, Role hierarchy I presented. But just to save you from looking up all the references, here are the parallels:* Tier 1Identity - "A constant that cannot change."Personal - "timeless and unconditional."* Tier 2Persona - "An application of my identity to a broad situation - my office persona, my parenting persona or whatever.\u00a0 It applies my identity to a specific situation."Corporate - "We typically denote these identities as being assigned or issued to us, and they typically refer to us in the context of a business relationship."* Tier 3Role - "A specific application within a persona. In my office persona, I may have a manager role, a mentor role, an employee role, etc."Marketing - "The way in which companies aggregate us into different marketing buckets."It's not a true congruence of ideas: Durand's Tiers 2 and 3 don't match up exactly with mine but put him in a room with Ed Harrington and I'm sure they could refine the taxonomy. And, after all, that's exactly what Harrington wants to do - create a taxonomy to facilitate discussion of identity management issues and principles. Read Durand's essay, then re-read last week's newsletter ("Defining identity, persona, role") and reach some convergence yourself. Find out if great minds really do think alike.