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In milk there is a fatty element, which in clotted milk gets to
resemble oil. Goat's milk is mixed with sheep's milk in Sicily, and
wherever sheep's milk is abundant. The best milk for clotting is not
only that where the cheese is most abundant, but that also where the
cheese is driest.

Now some animals produce not only enough milk to rear their young,
but a superfluous amount for general use, for cheese-making and for
storage. This is especially the case with the sheep and the goat,
and next in degree with the cow. Mare's milk, by the way, and milk
of the she-ass are mixed in with Phrygian cheese. And there is more
cheese in cow's milk than in goat's milk; for graziers tell us that
from nine gallons of goat's milk they can get nineteen cheeses at an
obol apiece, and from the same amount of cow's milk, thirty. Other
animals give only enough of milk to rear their young withal, and no
superfluous amount and none fitted for cheese-making, as is the case
with all animals that have more than two breasts or dugs; for with
none of such animals is milk produced in superabundance or used for
the manufacture of cheese.

The juice of the fig and rennet are employed to curdle milk. The
fig-juice is first squeezed out into wool; the wool is then washed and
rinsed, and the rinsing put into a little milk, and if this be mixed
with other milk it curdles Rennet is a kind of milk, for it is found
in the stomach of the animal while it is yet suckling.