There are certainly laws and elements that make a film more accessible to mainstream audiences. If you've got Tom Cruise as a strongman, I'm sure it would have larger audiences, but it wouldn't have the same substance.

Chauvet Cave is rather like the awakening of the modern human soul or I would say the awakening of modern human culture. Because Neanderthal men who still rode the landscape parallel to the people who did these paintings didn't have culture. There's no evidence of culture, no symbolic depiction, no evidence of music, no evidence of sculptures, no evidence of religious beliefs.

It's curiosity, and always a sense of poetry. You see it in particular in the chapter "Iceland" where I'm reciting ancient Icelandic poetry. It has this very beautiful gravitas in conjunction with the volcanoes.

Do you not then hear this horrible scream all around you that people usually call silence.

The wonderful thing is that Clive [Oppenheimer ] insisted on training his camera - his private camera - on me at one point. We were discussing things such as how to avoid certain dangers, while reflecting on a volcano that had threatened to explode 40 years ago.

Clive [Oppenheimer] and I figured out that I'm the only one probably in the film industry who is clinically sane. I say that as a joke, but there's a grain of truth to it. I'm not a stupid daredevil who jumps into the crater of the volcano to get the closest close-up, I'm not one of those. And you have to be aware that you have a crew with you and you are responsible.

Maybe I should stay a good soldier of cinema.