Subject and Predicate?

This week in class we discussed the idea of the subject and the predicate when it comes to the "is" of artistic identification. Is, is a form of the verb "to be" which is used in everyday spoken language quite frequently. An example of a simple predicate is saying something is something. For example, a mother holds up a glass of milk and says to the baby, this is milk. Another form of a subject predicate is with the indirect predicate. The phone rings. A man on the other line of the phone says Kim? Kim says this is she. The is is the predicate to Kim which is the subject. Another form of subject and predicate is in the form of existential predicate. The saying, I think therefore I am, is an example of this. The to be is in the form of he exists due to he thinks. The final form of subject and predicate is the artistic predication. This form uses perceptual indistincutal counterparts to explain the differences between two very similar things. For example, A is something and B is a work of art. A is the variable to understand part of the whole that which B is art.

Now a question I pose is, if B is a work of art and A is something, where does C come into play?