In this week's Book Club podcast, I'm talking to Wendy K Pirsig – widow of Robert M Pirsig, author of Zen and the Art of Motorcycle Maintenance, the bestselling book of philosophy of all time. Wendy tells me about her late husband's big idea – the "Metaphysics of Quality", as set out in a new collection of his writings, On Quality, which she has edited – how fame (and bereavement) changed him, and how he sought to undo years of dualism in the Western philosophical tradition by recourse to Eastern teachings and, of course, the odd monkey-wrench.