Terry Gross

There are 10 times more microbial cells on and in our bodies than there are human cells. And these bacteria aren't just there for the ride. Dr. Jeffrey Gordon explains how they contribute to the physiology of the human body and why they may hold the key to fighting some diseases.

Many of Spencer's novels feature a turning point -- a dreadful, unplanned act committed by one of the characters. In his latest book, Man in the Woods, a carpenter accidentally kills a man, which leads him to question himself and his relationship with God.

In Making Our Democracy Work: A Judge's View, Supreme Court Justice Stephen Breyer outlines his ideas about the Constitution and about the way the United States legal system works. Breyer explains how the justices debate each case on their docket, why he interprets the Constitution as a living document, and details what he thinks is the worst decision the high court has ever made.