Measuring the influence that a secondary work — most commonly a biography or a larger history — wields in a historiography is an effort that requires looking at various factors. Obviously, one of the most telling indications of a book’s influence involves its sales. This is a perfectly valid rubric: after all, even the most well-written, revelatory and well-researched book would have little-to-no impact if no one bothered to read it. Certainly, it’s no coincidence that many of the most influential books in the band’s historiography — The Authorized Biography, Shout!, Revolution in the Head, The Beatles Anthology, Tune In — are also among the works that have moved the most copies, and are available in multiple, revised editions.
But attention to sales is only part of the picture. What’s easier to overlook, but just as crucial to the influence wielded by a secondary source, is the ripple effect involved when certain works become widely regarded cornerstones of a historiography. These works are then granted further validity when other secondary authors, both popular and academic, employ them as research tools, basing significant elements of their own interpretation on those provided by the cornerstone works. In this pattern, these other authors who unquestioningly use it become implicitly invested in affirming the cornerstone work; by using it in their own studies, they incidentally buttress its reputation, perpetuate the original work’s findings and spread its influence.