281. A noun used to describe another, and denoting the same person or thing, agrees with it in case. The descriptive noun may be either an appositive (§ 282 below) or a predicate noun (§ 283 below).
282. A noun used to describe another, and standing in the same part of the sentence with the noun described, is called an Appositive, and is said to be in apposition.
Externus timor, maximum concordiae vinculum, iungēbat animōs. (Liv. 2.39)
Fear of the foreigner, the chief bond of harmony, united their hearts.
[Here the appositive belongs to the subject.]
Quattuor hīc prīmum ōmen equōs vīdī. (Aen. 3.537)
I saw here four horses, the first omen.
[Here both nouns are in the predicate.]
Litterās Graecās senex didicī. (Cat. M. 26)
I learned Greek when an old man.
[Here senex, though in apposition with the subject of didicī, really states something further: viz., the time, condition, etc., of the act (Predicate Apposition).]
a. Words expressing parts may be in apposition with a word including the parts, or vice versa (Partitive Apposition.
Nec P. Popilius neque Q. Metellus, clārissimī virī atque amplissimī, vim tribūnīciam sustinēre potuērunt. (Clu. 95)
Neither Publius Popilius nor Quintus Metellus, [both of them] distinguished and honorable men, could withstand the power of the tribunes.
Gnaeus et Pūblius Scīpiōnēs
Cneius and Publius Scipio (the Scipios).
b. An Adjective may be used as an appositive.
Ea Sex. Rōscium inopem recēpit. (Rosc. Am. 27)
She received Sextus Roscius in his poverty (needy).
c. An appositive generally agrees with its noun in Gender and Number when it can.
Sequuntur nātūram, optimam ducem. (Lael. 19)
They follow nature, the best guide.
omnium doctrīnārum inventrīcēs Athēnās (De Or. 1.13)
Athens, discoverer of all learning
Note— But such agreement is often impossible.
Ōlim truncus eram fīculnus, inūtile līgnum. (Hor. S. 1.8.1)
I once was a fig-tree trunk, a useless log.
d. A common noun in apposition with a Locative (§ 427) is put in the ablative, with or without the preposition in.
Antiochīae, celebrī quondam urbe (Arch. 4)
at Antioch, once a famous city
Albae cōnstitērunt, in urbe mūnītā. (Phil. 4.6)
They halted at Alba, a fortified town.
For a genitive in apposition with a possessive pronoun or an adjective, see § 302.6.
For the so-called Appositional Genitive, see § 343.d.
For the construction with nōmen est, see § 373.a.
Predicate Noun or Adjective
283. With sum and a few other intransitive or passive verbs, a noun or an adjective describing or defining the subject may stand in the predicate. This is called a Predicate Noun or Adjective. The verb sum is especially common in this construction, and when so used is called the copula (i.e. connective). Other verbs which take a predicate noun or adjective are the so-called copulative verbs signifying to become, to be made, to be named, to appear, and the like.
284. A Predicate Noun or Adjective after the copula sum or a copulative verb is in the same case as the Subject.
Pācis semper auctor fuī. (Lig. 28)
I have always been an adviser of peace.
Quae pertinācia quibusdam, eadem aliīs cōnstantia vidērī potest. (Marc. 31)
What may seem obstinacy to some, may seem to others consistency.
Êius mortis sedētis ultōrēs. (Mil. 79)
You sit as avengers of his death.
Habeātur vir ēgregius Paulus. (Cat. 4.21)
Let Paulus be regarded as an extraordinary man.
Ego patrōnus exstitī. (Rosc. Am. 5)
I have come forward as an advocate.
Dīcit nōn omnīs bonōs esse beātōs.
He says that not all good men are happy.
a. A predicate noun referring to two or more singular nouns is in the plural.
Cōnsulēs creantur Caesar et Servīlius. (B. C. 3.1)
Cæsar and Servilius are elected consuls.
b. Sum in the sense of exist makes a complete predicate without a predicate noun or adjective. It is then called the substantive verb.
Sunt virī fortēs.
There are (exists) brave men.
Cf. Vīxēre fortēs ante Agamemnona (Hor. Od. 4.9.25)
Brave men lived before Agamemnon.