Van Helmont's account brings us face to face with a number of riddles. Certainly, there is nothing strange to us in his describing carbon dioxide gas as being 'finer than vapour and denser than air'; but why did he call this a 'paradox'? What prevented him from ranking it side by side with air? As to air itself, why should he describe it as belonging to the realm of the 'uncreated things'? What reason was there for giving 'vapour' the rank of a particular condition of matter? And last but not least, what was the ancient conception of Chaos which led van Helmont to choose this name as an archetype for the new word he needed?