ance-of (?instance ?class))
&gt; &gt;             (and (Entity ?instance)
&gt; &gt;                  (Class ?class))))
&gt; &gt;
&gt; &gt; ;; Axioms for the *constant* "Entity".  Syntactically, we can treat
&gt; &gt; ;; the predicate `Entity' and the constant `Entity' as distinct things
&gt; &gt; ;; that look the same;  alternatively, we can simply allow `Entity' to
&gt; &gt; ;; be both a predicate and a constant.  Semantically, the interpretations
&gt; &gt; ;; of the predicate "Entity" and the constant "En