Interesting about Martial.
The reason why I started worrying myself about subjects and predicates is because of infinitives. When I was reading about infinitives w/o subject accusative, Bennett says that when such an infinitive is used as the subject of a sentence:
... it may take a Predicate Noun or Adjective in the Accusative; as
aliud est īrācundum esse, aliud īrātum, it is one thing to be irascible, another to be angry
So I started thinking about Predicates and got myself completely confused. According to that definition, "esse" is the subject, "est aliud" the predicate and "iracundum" is the predicate adjective.
But doesn't a predicate adjective connect to the subject through a copulative verb which is "est" in this case? I.e., in my mind, it should not be right next to "esse", which is before the copulative verb. And yet, that's the only place it makes sense.
So where's what and why?