Phantasms of the Living, published in 1886 under three names but written mostly by Gurney, was an attempt to do something nobody had tried: to treat a mass of ghost stories as a body of evidence with rules. Its subject was the crisis apparition, the report of seeing or hearing a person at approximately the moment of that person's distant death or serious injury. Gurney set conditions for admitting a case, requiring a first-hand account from the percipient, corroboration from someone told before the outcome was known, and documentary confirmation of the timing where it could be had, and he discarded a great many reports that failed them. He then argued statistically that coincidences of this kind occurred far more often than the death rate would allow.
The critical response was immediate and has not been improved on much since: the recruitment of cases was not random, memory reshapes an experience once the outcome is known, and the base rate against which coincidence was measured rested on assumptions that could be disputed. The book nonetheless established that the question could be posed in evidential terms at all, and the collection remains a substantial documentary record of what late Victorians reported.