“None of the dozens of conspiracy theories about his assassination provided any solid evidence to change the sad conclusion that we simply do not know …. Some authors have speculated that Kennedy’s assassination was the work of powerful financial, military and intelligence community interests who feared that Kennedy might reverse not only racial discrimination but also anti-Communist belligerence. If history ever proves that horrific thesis correct, and those conspirators hoped by killing Kennedy to block the civil rights and peace movements in this country, one thing is clear — they failed.”
— Former JFK speechwriter Theodore Sorsensen, in the preface to the 2009 edition of his book Kennedy, p. xiii. (see in Google Books).