An unlikely suspect: CIA master spy James Jesus Angleton is said to have first mastered the dark arts of counter-intelligence during the Cold War studying.......English literature. The idea is that the close scrutiny of every scrap of intelligence, the willingness to read against the grain, the constant effort to assess ambiguity cumulatively makes for an analytical style equally useful for John Donne and KGB dispatches. See the interesting attempt to make the connectionhere.