I had always admired the H. Rider Haggard adventure story, “King Solomon’s Mines,” and I wanted to write a similar sort of Victorian adventure, set in the 20th century. I was also interested in the experimental attempts to teach apes to use language, and the implications of this research for animal rights, which in the late 1970s was a very obscure topic.

When the book was published, most reviewers found the character of Amy, the sign-language-using gorilla, too incredible to believe. This despite the fact that I had modeled Amy on a real signing gorilla, Koko, then at Stanford University. I considered Koko to be pretty famous. After all, she had been twice on the cover of National Geographic magazine, and once on the cover of the New York Times magazine. Koko had also been interviewed on television, where with quick hand gestures she complained about the bright lights, and told the TV interviewer to go away. But apparently, book reviewers had never heard of Koko.

To prepare for writing the book, I planned to go to Africa to see gorillas on the slopes of the Virunga volcano chain in eastern Congo. But at that time, there was a war between Tanzania and Uganda, and the eastern Congo were much too dangerous to visit. No one would take me there.

So I had to find substitutes. To experience volcanos, I went to Stromboli, off the coast of Sicily, a volcano which is continuously active. In those days you could just hike to the rim and watch the display as long as you wanted. For an experience in the rain forest, I went to Taman Negara in the jungles of Malaysia.

I never saw gorillas in the wild until two years after the book was published. Then I went to Rwanda, climbed the real volcanoes, and visited the real gorillas. This was a very powerful and emotional experience, which I wrote about in the book Travels.