In his work Meteorology, Aristotle explained that the earth as an element was cold and dry. He did not cover phenomena related to terrestrial heat. De Proprietatibus Elementorum filled this lacuna with its inquiry on volcanoes and hot springs. According to the work large quantities of sulfur in the interior of a mountain caused volcanic eruptions. Winds and waters present at the foot of the mountain could set fire to this sulfur, particularly in the case of Mount Etna.