When our lights turn on with the flip of a switch or a cross-country flight arrives on time, we don’t think about the people who worked hard to make sure those things happened. It’s only when things go wrong that we consider their roles. As part of our special Labor Day episode, we’ll listen back this hour to our conversation from June with David Zweig. He writes about the nameless, faceless people who keep our world running in his book Invisibles: The Power of Anonymous Work in an Age of Relentless Self-Promotion.