The informed breadth and depth suppose a state of information which lies somewhere between two imaginary extremes. These are, first, the state in which no fact would be known, but only the meaning of terms; and, second, the state in which the information would amount to an absolute intuition of all there is, so that the things we should know would be the very substances themselves, and the qualities we should know would be the very concrete forms themselves. This suggests two other sorts of breadth and depth corresponding to these two states of information, and which I shall term respectively the essential and the substantial breadth and depth.

By the essential depth of a term, then, I mean the really conceivable qualities predicated of it in its definition.

The essential depth of a term which is sometimes called its essence consists of the really conceivable qualities predicated of it in its definition. This is one of the most important features of logic.