John Nedwidek, a reader, wrote to share this anecdote from his experience learning Pixar's Showplace program in the early 1990's. (Showplace, long since discontinued, was a consumer-oriented program for creating 3D scenes; it was one of several products in Pixar's effort, pre-Toy Story, to refashion itself from a computer hardware company into a software company.)
When I was learning Showplace I called the Pixar help line a fair number of times. I usually spoke with a guy named Ed. He was very patient and knowledgeable. He told me how to get into the guts of Renderman – including how to adjust the settings of the carpet shader to affect the appearance of vacuum marks. Nice! A few years later I attended a SIGGRAPH show (we had some clients exhibiting) and I wandered over to the Pixar booth. Lo and behold, there was Ed Catmull. I introduced myself and mentioned how much I liked working with Showplace and that "Ed the help guy" was a great resource. I'm sure you've guessed now that they were one and the same. I never even considered the possibility.