 2. I cannot, however, think that one idea is a sufficient prerequisite for a judgment. I cannot see how there can be Belief without both a subject and a predicate. If you say that the idea of an elephant suffices for belief in an elephant, belief in an elephant can only mean belief that there is such a thing as an elephant—that an elephant exists: or, in other words, that under some circumstances, and in some place known or unknown, I should perceive by my senses a thing answering the definition of an elephant. Now this, which is the truth really believed, is a fact, in two terms, not in one  only.[15]  (Mill 1872 [1972: 1928–9])