I discovered Robert Caro’s work on Lyndon Baines Johnson more than twenty years ago.  I bought the first two volumes, The Path to Power,and Means of Ascent (neither in the VPL collection), from a discount table for no better reason than curiosity, and that Johnson had been President of the United States when I was born in the early part of 1964.  Even then (1991), I had formed an opinion of the relative effectiveness of Presidents Kennedy and Johnson.
Kennedy had a great gift for foreign relations, demonstrated in his great skill in bringing the world back from the brink of nuclear holocaust during the Cuban Missile Crisis.  He very likely would have conducted the war in Vietnam far differently than Johnson, and it would not have been the national disaster that it became.
Domestically though, it is a far different story.  Kennedy and the men who surrounded him were passionate about social justice and civil rights.  Yet, despite his eloquence, charm, wit, and personal magnetism, Kennedy was unable to realize his ideals through the required legislative action.  In fact, one of the qualities that drew men to him, his willingness to credit both sides of an argument, was the quality that kept him from having any meaningful domestic successes.  It was left to Johnson; coarse, uncouth, blustering, bullying Lyndon Johnson to put into action what the urbane Kennedy could not.
While the Civil Rights Act of 1964 was passed, at least partly, on a wave of emotion following Kennedy’s martyrdom, Lyndon Johnson was no mere caretaker.  He was a true believer.  While Kennedy and his followers may have seen the end of segregation as something greatly to be wished for, they did not understand it viscerally in the way Johnson did.  He had witnessed it, lived it, in a way that the Kennedy people had never known.  So, it was not just a political calculation to continue the Kennedy legacy, but Johnson’s deeply held belief in civil rights, coupled with his intimate knowledge of legislative processes, that propelled the legislation into law.
So far I am not as convinced as the author that, had he lived, Kennedy would have ever been able to achieve meaningful civil rights legislation, never mind all the other landmark domestic legislation passed under Johnson.  Perhaps the author will convince me in his next volume.
After reading this fourth volume, I am more convinced than ever that the mystique and admiration surrounding John Kennedy in life and death had more to do with his personal magnetism, his charisma, than with anything that he had actually achieved as the Chief Executive.  For those who followed him in life, and those who continued to do so after his death, the fascination had little to do with his accomplishments, but was and is, mostly a cult of personality.