Volume Three is this… is this book about… about sorting and… and searching, a field that… that was… that was changing greatly as… at… at the time I was… I was making the final version of that. So, I'm thinking about… I'm thinking about sorting and searching as I'm in Princeton. You know, I've finished Volume Two and I'm ready to come to Stanford, and… and… but… but I'm getting new ideas about… about sorting all the time because the field is changing. So, after I arrive at Stanford, I have to teach courses and start brand new things that I've never done before, so it took a while, and I wasn't able to finish Volume Three until I was in Norway in… in 1972 – that was my sabbatical year. It wasn't really a sabbatical year. I called it a sabbatical year, but it's… it's a leave of absence. I had been 3 years at Stanford, and I… I thought, oh, it would be great… professors are supposed to get 6 years and then… then a sabbatical, and then 6 years and a sabbatical. I thought, maybe I'll go on a 4r year cycle. I'll go 3 years, a leave of absence, then 3 years and a sabbatical. That was okay with Stanford's rules. And so, I… I got an offer from the University of Norway to spend a year there as a guest professor and I didn't need financial support from Stanford, so I could… so I could do that on a leave of absence without the… without the, you know, the problem of… of who's going to pay for it.
 
And I loved Norway – we had visited there in 1967, believe it or not. That was another thing that happened in 1967! And so I fell in love with that… with that country… in fact, the Norwegian National Anthem – Ja, vi elsker dette landet – we… we love this country. And so I… I went to Norway and that was where I… I completed Volume Three and began to work on… on Volume Four. The… that… during that year I… I gave lectures at the university every Wednesday, and… and stayed at home and did my… my book writing and reading and… and taking care of my kids the rest of the time.

So, finally then Volume Three came out and it was… it was… added a new dimension to this whole idea of analysis of algorithms, because when you start talking about the… about the topics that are in Volume Three, it turned out that… that there were many – even though the… it's talking about particular things, sorting, searching – the lessons that you're learning apply to many… many other things, and so… and so that was why Volume Three was… was especially important for me, that it… the paradigms, the methods that we use to study algorithms of all kinds all… seemed all arise in the context of sorting.  So I could make a… a unified story about it, but also… I mean… but… so I’m teaching general principles while… while being able to illustrate them around the special thing of sorting and searching.