It is an old truism that the British Labour Party owes more to Methodism than to Marxism. Elsewhere this is not the case. The Soviet Union and Communist China both elevated the ideas of Karl Marx, who was born on 14 May 200 years ago, to the status of holy writ, thereby influencing for better or for worse – and almost always for worse – the lives of a substantial proportion of the world’s population. Whenever he is invoked, for instance in British politics today, the crimes committed in his name are recited to blacken the reputation of all who stand, however remotely, under the umbrella of his ideology. Such is the damage it did. As Pope Benedict once remarked, there is nothing in the world as dangerous as a bad idea.