No / This paper draws a comparison between the 700-year-old historically reported will-o'-the-wisp phenomenon and the more recent discovery of extremophilic colonization of hostile environments; both have been observed as present in isolated, stressed environmental regions and originating from biological phenomena. However, whereas extremophilic activity can be understood in terms of a survival strategy based upon the synthesis of specific suites of protective biochemicals which are designed to control biogeologically the stressed habitats and to provide protection against the extreme environments, the analytical techniques that have proved so successful for the illumination of these survival strategies of extremophiles and which are now being miniaturized for in-field studies and for extraterrestrial exploration have not been applied to a clarification or evaluation of the phenomenon of will-o'-the-wisp. The reason is simply that the will-o'-the-wispsightings have now disappeared completely. Tantalizingly, all of the most reasonable physico-chemical and biological explanations for the will-o'-the-wisp phenomenon proved to be unsatisfactory in some respect and it is clear that, just as in the case of extremophilic colonization, will-o'-the-wisp would benefit from a modern rigorous analytical study which would produce the data from which the potentially novel biological behaviour could be characterized and which would help a better understanding to be made of our natural world.