Maybe there's something I'm missing, but I don't really understand the author's focus on monetary value here. The question I would be asking is: how is the capa

Maybe there's something I'm missing, but I don't really understand the author's focus on monetary value here. The question I would be asking is: how is the capability of the individual changing? There is little point in comparing the value of a journey by horse four hundred years ago to the same journey by aeroplane today. To reduce each to a numerical value feels like a conflation that makes this argument deeply flawed at minimum.