 Such an application of mathematics violates a traditional Aristotelian prohibition against metabasis eis allo genos, grounded on quite reasonable considerations. The basic idea is that things cannot be legitimately compared in any respect in which they differ in species. Thus it makes little sense to ask whether the soprano’s high C is higher or lower than Mount Everest—much less to ask (quantitatively) how much higher or lower it is. But for Aristotle, straight lines and curved lines belong to different species of lines. Hence they cannot be meaningfully compared or measured against one another. The same holds for rectilinear motion and circular motion. 