Donald Trump's illegal retention of classified U.S. government records reminded me that, in my capacity as a scholarly writer of international history, I have been reading these kinds of sensitive official files -- and learning from them -- for decades.  My research in U.S., British, Soviet, and East German records not only unearthed a good deal of information about great power behavior during the Cold War but, also, taught me how zealously governments guard their secrets.  In this context, it's possible that Trump's decision to hold onto classified files reflects a desire to withhold evidence of his own administration's extraordinary record of duplicity and malfeasance.