Donald Thurber was a Harvard chum of Jack’s. He relayed his impressions of Kennedy to another biographer,
He was a person who would ask questions of you, who would challenge your assumptions, not unpleasantly, but he would ask you, “Why do you feel that way? What makes you think so?” And, then he would continue a line of questioning as long as it interested him – and then, having sucked the orange dry, he would go onto another piece of fruit. You got the impression that here was a mind that was learning from other people, and that longed to learn from other people – he would regard them as sources of information and knowledge to fill out his own. The questioning was never ruthless; he never just shucked you off when he was through questioning you, but he wanted to know what you knew.
[3, p. 241-2]