Aristotle has rightly been called a 'universal genius'. Whilst his work in economics was not fundamental, it has nevertheless attracted an enormous literature. This is particularly true of some passages in his 'Politics' on the 'Natural' and 'Unnatural' modes of acquiring wealth and some pages in his 'Nicomachean Ethics' on the question of justice in exchange. Aristotle's views on the practice of usury and the doctrine of 'just price' have been heatedly debated from the Middle Ages to the present day.