Robert McCrum: I wouldn't normally be drawn to books about finding yourself but Jennifer Kavanagh's The O of Home is touching and inspiring in a way that brings to mind Thoreau's Walden
At one time, 'self-help' books were considered a little odd. Now they have moved into the mainstream and the new 'science of happiness' has become a cultural orthodoxy. Carole Cadwalladr asks if this vogue for positive psychology really helping anyone?