A Journey to the Center of the Earth is a classic 1864 science fiction novel by Jules Verne. The story involves a German professor Professor Von Hardwigg who believes there are volcanic tubes going toward the center of the Earth. He, his nephew Axel and their guide Hans encounter many adventures, including prehistoric animals and natural hazards, eventually coming to the surface again in southern Italy. One of Verne's main ideas with his stories was also to educate the readers, and by placing the different extinct creatures the characters meet in their correct geological era, he is able to show how the world looked a long time ago, stretching from the ice age to the dinosaurs. Henri Ellenberger writes that the book "could be interpreted in all its details as a journey through the unconscious with the discovery of deeper and deeper archetypes, until the encounter of a fireball (symbol of the spirit) sets about the enantiodromia, that is the reversal of regression and the return to the common world."