In an era when humans spend much of their time indoors staring at the dim glow of a screen, many of us have forgotten the simple pleasure of a stroll through a wooded glen, a hike up a secluded mountain path, or a nap in the grass. Many of us have a dog or go to the beach occasionally. But is that enough? In “The Nature Fix,” prize-winning science journalist Florence Williams asks, "What if?" What if something serious is missing from our lives? What if an occasional trip to the neighborhood park isn't enough?