By coincidence, I listened to this 2012 biographical interview only a few days ago. This is a good summary of his life's work. He was unbelievably lucid at age

By coincidence, I listened to this 2012 biographical interview only a few days ago. This is a good summary of his life's work. He was unbelievably lucid at age 94, and more recently. https://www.bbc.co.uk/programmes/b01h666h https://www.bbc.co.uk/programmes/b01h666h