The classical world was dotted with a number of locations from which subterranean gasses issued, many of which are still active. The most famous of these, at Delphi, is accompanied by a number of less well-known yet influential sites. In the case of Hierapolis, the Plutonium afforded a more deadly version of the Delphic reliance on earth-born gasses, while at Chimeras, a methane-based gas still burns. In this class of religious interpretation of natural phenomena can also be placed the use of mind-altering substances and privation-induced hallucination that played substantial roles at sanctuaries of Asclepius (amongst others). While there is a temptation in modern thinking to dismiss the actions of the priesthoods associated with these sorts of cults as cynical means of control over worshippers, I argue that this sort of religious action has more significance. A substantial shift in thinking that characterizes Greek philosophy from the Aegean region throughout the centuries preceding and including Alexander's campaigning concerns understanding the natural world and the implications that such thinking had for the world of the divine. In this paper, my goal is to examine how the work of the physiologoi and Aristotle forms part of a cline of development directly derived from cult. Several first-century CE authors will form a terminus to my investigation, which suggests that this cline--far from a mere philosophical exercise--continues in its religious importance well into Late Antiquity.