I had a chance to see him at the Business of Software conference in 2011. Incredible mind. He will be missed.
Here's the video of his talk: https://vimeo.com/63125209
Here's the video of his talk: https://vimeo.com/63125209
Of note: I don't think he started his PHD until he was 50. I wish more people at this stage of their lives pursued his sort of deep, meaningful research combined with personal reflection and experience.