 Marie Brennan remarked in 2008 that "the term has been around for a while without anybody ever achieving consensus on what it refers to" and proposed a broad definition that "it’s any story that treats magic like science" or fantasy stories that "are concerned with "how stuff works, and why"".Brian Stableford in "The A to Z of Fantasy Literature" concurred that the term "is used in several different ways", all attempting to create an analogy with the term hard science fiction with first definitions being reserved for works that are "scrupulously faithful to historical and anthropological data" outside having some magic or myth plot elements, and later definitions being more broad.John Clute and John Grant in "The Encyclopedia of Fantasy" defined it as a genre where "magic is regarded as an almost scientific force of nature and subject to the same sort of rules and principles", and which "might refer to fantasy stories equivalent to the form of hard sf known as the ‘scientific problem’ story, where the hero must logically solve a problematic magical situation".