In this powerful edition of Four Thought, recorded at the Hay Festival, the writer Matt Haig describes how words helped him live with depression.

"You have to believe there is a point of there being words, and that they can offer real meaning. Normally this belief is taken for granted, but that is because normally we are taking the world itself for granted. But when your mind crumbles to dust everything you thought you knew suddenly becomes something to question. You have to build reality up again. And the bricks we use to shape our realities are called words."

Recorded at the Hay Festival.

Producer: Lucy Proctor