Judgments are divided by Kant into two large classes,――analytic and synthetic. The large class of analytic judgments are not expressions of knowledge. What is an analytic judgment? An analytic judgment merely expresses in the predicate something that is contained in the usual meaning of the subject. Such a judgment articulates the meaning of an idea by emphasizing some of its well-known attributes. Thus we say, “Gold is yellow.” Such a statement about “gold” does not show any knowledge. It is called sometimes an explicative statement. It is tautologous, but not on that account trivial. Let us look then to synthetic judgments to see if they express knowledge. But first, what is a synthetic judgment? A synthetic judgment is one in which the predicate is not contained in the usual meaning of the subject. It is a statement of something new about the subject in hand. For example, the judgment, “The watch is yellow” is a synthetic judgment because the predicate “yellow” is not a necessary part of the meaning of “watch.” A synthetic judgment therefore brings two ideas together in a new relation. It thereby enriches knowledge and is the expression of discovery. The synthetic judgment is often called ampliative. (The double meaning which Kant gives the term “synthetic” need not confuse us. Synthesis is used by Kant to mean the framing constitution of the mind, and also as one of the results of the activity of the mind, _i. e._ a class of judgments. In the first sense all judgments, both analytic and synthetic, are expressions of synthesis.) Are all synthetic judgments expressions of knowledge? Kant replies that they certainly are not. He points out that there are two classes of synthetic judgments: one class he calls _a posteriori_ and the other _a priori_. By _a posteriori_ he means judgments founded in some sense-perception, which are particular judgments or judgments that are inferences from a greater or less induction of sense-perceptions. For example, if I say, “To-day is warm,” or that “Swans, so far as I have observed, are white,” I am making a synthetic judgment, because I am joining two ideas in a new relation, and I am also making an _a posteriori_ judgment, because it is a statement founded upon sense-perception. Now Kant rules such judgments out from those that constitute true knowledge. This would rule out even empirical generalizations of high probability, such as “The sun rises in the east.” _A posteriori_ judgments, or those founded on experience, however large, do not give us knowledge, but merely probability. The cases upon which such judgments are founded are always limited, and there may be exceptions beyond our observation.