I'd always been... perhaps just that army training, I don't know, but I'd always been very physically fit. And I came back and I just collapsed; I was seriously ill with hepatitis. I think they may have done something to my food, I'm not sure. But anyway, I had this hepatitis and I was out of action for weeks and weeks. And it was during this time that I realised that I'd been overworking. I now had two television series going, I had a curatorship at the zoo, I was doing book reviews for Times Literary Supplement, I was writing a book a year, and I was just overworking – and I had a whole research team. It wasn't that... I wasn't... I was enjoying it all, that's why I wanted to do it all and I was loving it all, but I was only one human being and I couldn't... I just couldn't do it.
So when I lay there very ill, after Moscow, I decided to stop doing a lot of things. I stopped book reviewing and I stopped this and I stopped that and I cut down on all my activities. And in... this was in 1966 and I said I'm just going to do one thing: I'm going to finally sit down and write The Naked Ape, this book that I've been putting off. Instead of doing all these different things, I'm going to do one major thing. And that's how I came to write The Naked Ape. So in a way I'm grateful to Moscow, because if I hadn't been ill after Moscow, I probably wouldn't have reorganised my life and written The Naked Ape.