Are ex-presidents a help or hindrance?

For a generation, Americans have had a historically large number of ex-presidents around, a possible source of counsel from one of only 45 people who have exercised the broad powers conferred by Article II of the Constitution.

You might expect former presidents to supply elements of personal comity and institutional norms to current politics, and sometimes they do. Certainly, the few periods with no living former presidents have been times of stress when incumbents might have called on seasoned predecessors for advice.