Oliver James is an assiduous trawler of the densest psychological and psychiatric studies to retrieve the nuggets of wisdom buried therein. He's also a modern day missionary, fired with a passionate desire to relieve the growing emotional suffering in rich countries, which has led the World Health Organisation to predict that depression is on track to become the second most widespread disease, after heart disease, in the developed world by 2020. His writing career has been an attempt to marry these two impulses (which can often tug in opposite directions) and thus bring to a wider public the growing body of research, particularly in the US, into what constitutes human well-being and why it appears to be in decline.