 In the context of modal logic, Prior called such propositions possible-world-propositions. Of course, this is what we here call nominals. Prior also introduced the binder \(\mathtt{\forall}\) and what we here call satisfaction operators (he used the notation \(\mathtt{T(a, \phi)}\) instead of \(\mathtt{@_a \phi}\) for satisfaction operators). In fact, Prior’s third grade tense logic is identical to the hybrid tense logic as defined above. The \(\mathtt{\downarrow}\) binder was introduced much later. Thus, Prior obtained the expressive power of his first-order earlier-later logic by adding to ordinary tense logic further expressive power in the form of nominals, satisfaction operators, and the binder \(\mathtt{\forall}\). So from a technical point of view he clearly reached his goal.