James Campbell's family were unusual. They were the 'singing family'. Everyone on their street knew it - and heard it. They would sing at the drop of a hat and James' father had a barbershop quartet.

Every Monday evening James would listen attentively to the sumptuous close harmonies and his father taught him and his siblings to harmonise too. James took this into his adult years. It gave him a lifelong enjoyment and confidence to harmonise with other people, just for fun. One day, when his father is taken very ill, James realises the power of harmony at the hardest of times as he and his family join around his father's hospital bed to sing.

In this episode, Matthew Syed explores the importance of harmony and asks whether bringing in musical ideas could help bring us a little more harmony in our lives. We get a lesson in close harmony singing with folk trio Lady Maisery and consider how the principles of close listening could carry beyond a musical setting.

And Matthew explores Plato's ideas about the soul in harmony with Professor Angie Hobbs, the Professor of the Public Understanding of Philosophy at the University of Sheffield. And with Ian Cross, Emeritus Professor of Music and Science at the University of Cambridge, Matthew unravels the ways we communicate musically in conversation to signal agreement and to bond, showing the vital importance of musical interaction in bonding.

Presenter: Matthew Syed Producer and Series Editor: Katherine Godfrey Executive Producer: Max O'Brien Music, Sound Design and Mix: Rob Speight Theme music by Ioana Selaru. A Novel production for BBC Radio 4.