Cato the Censor wrote that sheep’s milk had three uses: the first, in small quantities, was for religious purposes relating to sacrifice; the second was for drinking; and the third and most sizeable part was for making cheese. The rennet produced during the cheese-making process was used to make ricotta, medicine and to feed pigs.The agronomist Columella (1st century) closely observed the practice of cheese-making during his era and documented the ways in which cheese was prepared in Ancient Rome. He wrote how the milk obtained the evening before was processed at dawn the following day to prevent it from souring. It was poured into a wide pot and curdled by adding certain ingredients such as vinegar which, according to Columella, gave the cheese an excellent flavor, or cardoon flowers, safflowers and fig sap (as noted by Pliny the Elder). Donkey’s milk could also be used (as noted again by Pliny), but mainly the rennet was extracted from the intestines of lambs, kids, fawns and even young hares (as noted by Varro, Pliny and Athenaeus). To avoid giving the cheese an unpleasant flavor, it was recommended to only use a small amount of rennet. Varro (1st century) made the most detailed observations and suggested that the amount of rennet per 6.5liters/1.7gallons of milk should be no greater than the size of an olive. The milk had to be heated to a precise temperature for around an hour. The pan never needed to be placed directly over the fire but rather placed near the hearth. Columella also added that to flavor the cheese, it was customary to add particular flavorings to the curdling cheese such as almonds, pine nuts and thyme, which would be removed once the curd began to form. One important tip was to separate the rennet from the cheese as soon as possible.