There are three substances in milk: curds, whey, and butter; and that is not suitable when the strength is weak, as in the case of old people; therefore milk is not good for them. Galen is against this in his book concerning the maintaining of health. I say, according to the intellect of Galen and his mind, that milk is good for old people, and there have been people who lived a hundred years on milk as food; though it is necessary to digest it well in the stomach, without letting it form curds nor turn to windiness nor cause oppilations, hence it is not good for those who have narrow veins naturally unless salt and honey be mixed with it, that it form not curds nor oppilations nor turn to windiness and in this way it is good, for it is easy to digest, and penetrates easily and agrees, though it is not easy to eat anything else after it, till it be digested.