I had, at the last days of Project Matterhorn, been giving this course in gravitation and I produced notes there. But my biggest drive to produce notes came when I was giving lectures at the University of Kyoto, because I realized that my Japanese friends would not all understand English equally well, and therefore each day I wrote out in advance what I would be talking about and had these notes mimeographed so that everybody had a set of notes to look at, and that became a help in producing a book. But Charlie Misner and Kip Thorne also had their pushes to produce notes, and one time we were talking and we said to each other "We ought to make a book out of these things" - and we ended up in essence signing a treaty that we'd make a book. And Kip Thorne was a great organizer and he pulled these things together and we were very lucky to have a publisher who had good ideas how to put it together. We split the pages into easy things where one could quick get a view of the subject and we marked these with a big black-- visible from the corner of the book, and the other pages giving more technical detail. And we had an illustrator, a Japanese American - I'm trying to remember his name right now - but he fulfilled my ... He went by the nickname 'Ishy'. Yes, Ishikawa. I can't understand anything if I can't make a picture of it, and if you ask me to do - how I would make a picture of something so ephemeral, so strange as the idea of this being a self-generated universe, I would put a luminous pair of arrows like this pointing toward the future, and another luminous pair of arrows pointing toward the past. I don't know what the diagram means, but it's just an encouragement to me to have a diagram like that to help think about what it would mean to have a picture of how this universe is self-generated. Well, this book has a lot of references at the end, I think a thousand references, and thanks to the good sense of Kip Thorne we engaged somebody, who was good at looking up references, to get all these references. I wish I had his services day before yesterday when I was looking up unsuccessfully a paper by the Russian scientist Ivanenko on the collision of two gravitons to make a pair of positive and negative electrons. I never did succeed in finding the reference, but I know if I go hard enough at it, I can find it.