Tenses
As noted earlier, the three tenses of infinitives show time relative to the main verb. The relationships are the same as for participles. The present infinitive shows something happening at the same time as the main verb, the perfect infinitive shows time before, and the future infinitive time after.
Caesarem exercitum potentem habē
Caesarem exercitum potentem habuisse audiī. (perfect infinitive) I hear that Caesar had a powerful army. (time before)
Caesarem exercitum potentem habitū
Shouldn't the future infinitive of habeō be habitū rum esse ?
Strictly speaking, yes. Future infinitives, however, are quite frequently found without the esse. You can tell the infinitive from the participle by the construction. In indirect statement, for example, an infinitive would be called for.
These during, before, and after relationships are all relative to the tense of the main verb, whatever that tense happens to be. In the above examples, the main verb (audiī) is present tense. If we change it to the perfect, for instance, the meanings (i.e., translations) will shift as well.
Caesarem exercitum potentem habē
Caesarem exercitum potentem
Caesarem exercitum potentem habitū rum audī vī. (future infinitive) I heard that Caesar was going to have a powerful army. (time after)
