THE THINKING behind the screening of “El Cid” in New York City is a throwback to the kind of old-fashioned can-do liberalism represented by the movie itself. Think JFK. A vigorous liberalism which believes in goodness, humanity, and right versus wrong. Recall that in the movie, Rodrigo rejects extremists in both camps. His integrity carries the day against impossible odds, which makes him a noble figure. Doing what’s right, not expedient, is his ethos, his mission. This is what makes him a compelling figure throughout.