tity" may or may not 
&gt; turn out
&gt; &gt; ;; to be the same thing.
&gt; &gt;
&gt; &gt; (documentation "AXIOM:  Entity (the class) consists of exactly
&gt; &gt;  the entities (the things to which the `Entity' predicate applies )")
&gt; &gt;
&gt; &gt; (forall (?x)
&gt; &gt;         (&lt;=&gt; (Entity ?x)
&gt; &gt;              (instance-of ?x Entity)))
&gt; &gt;
&gt; &gt; ;; THEOREM: Entity is a class.
&gt; &gt;
&gt; &gt; (Class Entity)
&gt; &gt;
&gt; &gt; ;; PROOF: By the two preceding axioms, there is a