It's quite difficult to define what has been 'lost', let alone attach a timeline.  The nearly simultaneous rise of ignorance intentionally induced by 'progressive' education and the emergence of nearly universal access to information brought by the internet produces a fog of confusion where one doesn't know what is true or who to believe.  It's not easy to 'connect the dots' when they're hidden in a cloud of tantalizingly almost credible similar dots. So instead of history we have narratives--stories composed of selected events told from a specific perspective.  Change the viewpoint and the same events take on a completely different character.  We each cope with the intrinsic confusion in our own way, generally and unwittingly falling victim to the intellectual sin of bias--usually of confirmation or conformity. I take a somewhat unusual approach in an attempt to see more clearly through the fog.  I've defined my personal path as 'eclectic iconoclasm'; questing for truth by disbelief, researching the origin and context of anything and everything.  I realize that to some I appear to be an insufferable bore and relentless asshole even as we may share common principles; I respect anyone who can engage in a civil dialogue even in disagreement.  The object of the exercise is the exchange of ideas.