is only a schema. That is, it stands for the set of all sentences that are obtained from the above expression by substituting sentences of \(\mathcal{L}_T\) for the Greek letters \(\phi\) and \(\psi\). The single sentence \(\forall{\scriptsize A}\forall{\scriptsize B}(T[{\scriptsize A} \wedge{\scriptsize B}] \leftrightarrow  (T{\scriptsize A} \wedge T{\scriptsize B}))\) implies all sentences which are instances of the schema, but the instances of the schema do not imply the single universally quantified sentence. In general, the quantified versions are stronger than the corresponding schemata. 