The difference between man and beast was most sharply drawn by René Descartes, who in the 1630s argued that animals were mere machines or automata, like clocks, while humans had minds and souls. This soon became the standard view. Surely there could be nothing wrong with using soulless machines to plough your fields, or skewering a few for your evening meal. Medieval Britons rarely ate meat, but by 1726, Londoners were annually killing 600,000 sheep and 200,000 cattle