The tribe of economists to which I belong regard concepts as more or less ‘kosher', but not description. Economics, most of them would probably argue, is concerned with analysis and prediction; description is for lesser breeds. For example, students are taught the intricacies of analysing the supply of money, but it is rarely suggested to them that they might reasonably be expected to know how money actually comes into existence, which would involve knowing and being able to describe what a bank is, What it does and how. Confronted with such searching questions, they are therefore generally floored; and last year's students are, of course, this year's professional economists!

Yet description is really of the essence of any subject. We cannot account for economic change in Africa unless we can describe it.