As you would expect with a former leader of a major private institution, William G. Bowen is not an easy interview. He senses precisely when to hold back, removing any possibility of untoward statements. As a result, there isn’t much to work with. His latest book, “Lessons Learned,” recounts his days as president of Princeton University (1972-1988) in 168 pages, and provides some insight on leadership — including knowing when you’ve said enough.

But there’s still a lot about Bowen that is quite unexpected. He’s always leaned distinctly to the left of most university presidents — especially leaders of elite universities.

Over the years, he’s developed a progressive view of affirmative action, best expressed in “The Shape of the River” (2000), which he co-authored with former Harvard University president, Derek Bok, and further developed in last year’s “Crossing the Finish Line.”

Bowen says his slow learning curve on minority admissions is still among his greatest regrets — a lesson learned the hard way. “It was a result of not looking hard enough at data. I mistakenly thought that Princeton during my time had been more open to students for low socioeconomic backgrounds than it was,” he says. “I thought Princeton was giving disadvantaged students an extra break in that process and subsequent evidence showed that … we were not.”

But while Bowen points out that universities are not as “top-down” as other private institutions, he bristles at the idea of a thoroughly democratic university. “You don’t decide who to appoint or who to graduate by having plebiscites,” he says. “Rather, you have people with requisite credentials making careful judgments, which you then evaluate. And that’s the way it has to be.”