 As a result, Paul builds up a mixed system, where the copula of the standard philosophical sentences he deals with can have a threefold value: it means a partial identity between the subject-thing and the predicate-thing in the case of identical predication; it means a necessary link between forms in the case of the first type of formal predication; it means that the subject-thing in virtue of itself is necessarily a member of a given class of objects, which the predicate-term of the proposition labels and refers to, in the case of the second type of formal predication—that is, when the predicate is a term of second intention.