It is very difficult for ...

It is very difficult for [people] to accept the idea that someone as inconsequential as Oswald could have killed someone as consequential as Kennedy.
 Robert Dallek

Quotes from the same author

As someone who has more than a passing acquaintance with most of the 20th century presidents, I have often thought that their accomplishments have little staying power in shaping popular views of their leadership.
 Robert Dallek
... what's in a person's heart and soul will not likely be changed by the ability to command a helicopter to land on the South Lawn.
 Robert Dallek
The consequence of the Bay of Pigs failure wasn't an acceptance of Castro and his control of Cuba but, rather, a renewed determination to bring him down by stealth.
 Robert Dallek