Also submitted here: https://news.ycombinator.com/item?id=22530271

I'll repeat here what I said there:

I was privileged to know Richard and spend some time with him. He was a phenomenal mathematician, and a gentle soul. I will miss his wit, wisdom, intelligence, and conversation.

I love this anecdote in Young At Heart:

After his first day in kindergarten, three-year-old Richard told his parents, who were very eager to know how the day had gone, “It was all right, but the teacher doesn’t know much. She asked me what shape the world was and all sorts of things that I thought she would have known.”