One of the most popular radio programs in Britain in the 1940s and 1950s was The Brains Trust, in which a panel of intellectuals and entertainers, chosen for their skill with words and ideas, would debate questions raised by an audience or sent in by listeners. Over the years, many became household names, including the scholar and philosopher Professor C.E.M. Joad, whose thoughtful response to almost any question – ‘It all depends on what you mean by . . .’ – was greeted by the audience with the delighted and affectionate laughter with which they would greet the catchphrase of a favourite comedian. Many of his listeners would have had little understanding of the urge which prompted the preamble – Joad’s need to deﬁne the question, to delineate the grey areas, and to clarify precisely those aspects to which he felt he could respond; in the minds of radio audiences, ‘It all depends on what you mean by . . .’ became Joad’s leitmotif; something you could depend on for a chuckle of recognition before you settled down to try to understand his answer.