What does money tell us about human nature? How does it motivate, trick, satisfy and disappoint us? In this hour, TED speakers share insights into our relationship with money. Guests include psychologist Laurie Santos, behavioral economist Keith Chen, social psychologist Paul Piff, writer Daniel Pink and social scientist Michael Norton. (Original broadcast date: April 4, 2014).

For Martin Luther King, Jr. Day weekend, we hear from an unheralded civil rights activist known for his audacity, Dion Diamond. Also, voicemails from you, our listeners.

What are the five biggest global challenges we face right now — and what can we do about them? This hour, TED speakers explore some radical solutions to these enduring problems. Guests include geoengineer Tim Kruger, president of the International Rescue Committee David Miliband, political scientist Ian Bremmer, global data analyst Sarah Menker, and historian Rutger Bregman.

An unsolved murder, a child who wanted to do the right thing, and a lie that would put an innocent man in prison for nearly 40 years — in this episode, that wrongfully imprisoned man speaks with the person whose lie put him in prison.

Math intimidates a lot of us, but it can deliver surprising answers to life's pressing questions. In this episode, TED speakers discuss the elegant simplicity, and giddy complexity, of solving for X. Guests include comic book author Randall Munroe, polymath Terry Moore, percussionist Clayton Cameron and Mathematician Hannah Fry. (Original broadcast date: March 5, 2015)

To kick off the New Year, stories of people who have started over, turned the page, and wiped the slate clean. They did this sometimes to follow a dream, other times to escape bad ones.

Beauty surrounds us, draws us in, gives joy and creates conflict. In this hour, TED speakers conjure up beauty both ancient and modern, and suggest reasons why humans are hardwired to crave and respond to beauty. Guests include the late philosopher Denis Dutton, psychologist Nancy Etcoff, fashion model Cameron Russell, community activist Bill Strickland, and designer Richard Seymour. (Original broadcast date: April 19, 2013)

For New Year's, a 1994 documentary by photographer Richard Sandler and StoryCorps founder Dave Isay about street preachers in Times Square. See Sandler's work at instagram.com/ohstop1946/ and facebook.com/richardsandlerphoto. More at StoryCorps.org.

Our approach to treating disease is, in many ways, narrow and rooted in the past. Is it time for a new paradigm? This hour, TED speakers share their visions for new ways to understand medicine. Guests include cancer physician and writer Siddhartha Mukherjee, surgeon and writer Atul Gawande, neurosurgeon Jocelyne Bloch, and internist Joseph Ravenell.

Stories about the holidays bringing out the best in people. More at StoryCorps.org