This book about the psychology of morality analyzes the roots of our moral behaviour in society. The first part argues that intuitions come first and strategic reasoning comes after. The author, a professor at NYU's Stern School of Business, makes this point using a variety of convincing theoretical and empirical sources. The second part argues that morality is not only about caring and solidarity, the usual moral feelings of the left, but also about authority, sanctity and other values usually associated with the right. The main point here is that the left should show more respect for these other values, because they are as ingrained as cooperation and solidarity in the evolutionary roots of human behaviour. The third point is that humans need groups, that part of our institutional environment, which has become hardwired in our brains, has to do with belonging, and that this explains many aspects of political and religious behaviour. These are mainly "positive" points, explanations about why reality is the way it is. These are the most convincing aspects of the book. There are also here and there, however, many "normative" claims, that are in my view not necessarily derived from the more positive aspects. For example, the book ends with a chapter on the desirability of creating bridges between left and right that seem to me more a convenient value judgement than something that necessarily follows from the scientific parts of the book. Looking superficially to some of the book's reviews in the net, it seems that some reviewers criticized the author for this. I kept looking for references in the book about why some people change their moral beliefs during their lives, and although the book is not essentially about this, I found some useful ideas about the issue. People change their mind (for example, the auhtor became more open to the acceptability of conservative values during his life) because their intuitions (not necessarily their arguments) may be affected by other people's intuitions or arguments, and because of the influence of particular biographical turning points that alter our personal narrative and that make us fall into the basin of attraction of socially appealing stories. I'm trying to apply these ideas to some friends of mine who seem to have changed their mind in the recent past, from being left wing internationalists to becoming Catalan nationalists (at least one of them says that he hasn't changed his mind: OK...). Finally, I also found the book useful to explain the behaviour of sports fans (the importance of tribalism), something I will need soon because in one week I start two new groups of my course on the economics of soccer.