Cheese has been made and used as an article of food from a very early date. It was well known to the early Jewish patriarchs, and is frequently mentioned in the earliest Hebrew records. “Hast thou not poured me out as milk, and curdled me like cheese?” says Job; and David was sent to “carry ten cheeses to the captain of their thousand in the camp.” Most of the ancient nations, indeed, barbarous as well as civilized, made it a prominent article of food. But cheese, as made by the ancients, was found to be hard and brittle, and not well flavored, and means were devised to produce the same effect while the milk still remained sweet. It was observed that acids of various kinds would answer, and vinegar was used; and cream of tartar, muriatic acid, and sour milk, added to sweet, produced a rapid coägulation. In Sweden, Norway, and other countries, a handful of the plant known as butterwort (_Pinguicula vulgaris_) is sometimes mixed with the food of the cow, to cause the milk to coägulate readily. A few hours after milking, the curd is formed without the addition of an acid. Milk taken into the stomach of the calf was found to curdle rapidly, even while sweet; and hence the use of rennet, which is simply the stomach of the calf, prepared by washing, salting, and drying, for preservation. This acts the most surely, and, if properly prepared and preserved, is the least objectionable, of any article now known; and is, in fact, the natural mode of curdling the milk as it enters the stomach, preparatory to the process of digestion. Besides this, it is generally the cheapest and most available for the farmer. The richness of cheese depends very much upon the amount of butter or oily matter it contains. It may be made entirely of cream, or from whole or unskimmed milk, to which the cream of other milk is added, or from milk from which a part of its cream has been taken, or from ordinary skim-milk, or from milk that has been skimmed three or four times, so as to remove nearly every particle of cream, or from butter-milk. The acid used in curdling milk acts upon the caseine alone, and not upon the butter particles, which are imbedded in the curd as it hardens, and thus increase its richness and flavor without adding to its consistency, which is due to the caseine.