How should we think about fire? An answer is not obvious. It is testimony to the immense significance of fire that humanity has for so long chosen not only to anthropomorphize it but to grant it a substantive identity it does not deserve. Early philosophers considered it a god, or at least theophany, the manifestation of a god-like presence and power. The Aztecs called it Huehueteotl (or Dios viejo, the Old God), and the Hindus, Agni, along with Indus the most venerable of their pantheon. The Ancient Greeks, and the ancient Chinese, labeled it an element. For Western civilization it then morphed into a declination of lesser substances such as phlogiston and caloric before ending as a subservient chemical reaction, the rapid oxidation, usually accompanied by flame, of other substances. Today it no longer claims reality as an autonomous substance. Rather, fire is a phenomenon that derives from its circumstances. It is what results when heat, fuel, and oxygen combine under suitable conditions. It is a reaction, a process. It has no reality apart from the physical circumstances that make it possible. It synthesizes its surroundings. And that, in brief, is equally the lesson of its intellectual history. Fire’s definition has changed with its cultural circumstances. It takes its character from its context.