In the Seventies, when I came of age politically, being a lefty was all about believing that “the people” would always save us, if they just knew the truth. We were still immersed in the Century of the Common Man. We believed, as Henry Wallace once put it, that “the march of freedom of the past one hundred and fifty years has been a long-drawn-out people’s revolution.” The moral arc of the universe might be long, but the people, united, were pushing us more and more quickly along it.

This view was bred in the bone, our national religion…