From time to time newspapers invite writers to describe the ‘books that changed my life’. The resulting columns too often dazzle the reader with a display of erudition or passion, rather than tell the more mundane truth. The mundane truth is that our dispositions and the courses of our lives tend to be fixed before our ages run to two digits: a time when we were unlikely to be tackling Proust, understanding Nietzsche or appreciating C.P.