when you're trying to analyze text from documents of uncertain origin, one of the most powerful tools is to look for information that would be known to someone living in a particular place and time, but that wouldn't have been known to "outsiders" (ie, forgers) until after the manuscript was discovered. For example, if you find that a manuscript discovered in the early 1900s uses the right statistical distribution of names from a particular area in the 1600s, and that name distribution was determined from more recent archaeological finds, that suggests the document was written by someone from that time and place.
I wonder if he meant H.G. Wells, or if that was a reference to Back to the Future III.