Two of the most important characters of general terms are their logical breadth and depth. [—] The depth of a term is that which can be predicated of it. [—] The depth of a term cannot be considered as a collection of things but can only be considered as a complex of terms or of attributes. The term attribute, character, mark or quality is a term of second intention.
The totality of the predicates of a sign, and also the totality of the characters it signifies, are indifferently each called its logical depth.
…it was between six and seven centuries ago that John of Salisbury spoke of it as “fere in omnium ore celebre.” It is the distinction, to use that author’s phrases, between that which a term nominat – its logical breadth – and that which it significat – its logical depth. In the case of a proposition, it is the distinction between that which its subject denotes and that which its predicate asserts. In the case of an argument, it is the distinction between the state of things in which its premisses are true and the state of things which is defined by the truth of its conclusion.