452. The infinitive, with or without a subject accusative, may be used with est and similar verbs (1) as the subject, (2) in apposition with the subject, or (3) as a predicate nominative.1
- As subject.
Dolēre malum est. (Fin. 5.84)
To suffer pain is an evil.
Bellum est sua vitia nōsse. (Att. 2.17)
It's a fine thing to know one's own faults.
Praestat compōnere fluctūs. (Aen. 1.135)
It is better to calm the waves.
- In apposition with the subject.
proinde quasi iniūriam facere id dēmum esset imperiō ūtī (Sall. Cat. 12)
just as if this and this alone, to commit injustice, were to use power
[Here facere is in apposition with id.]
- As predicate nominative.
Id est convenienter nātūrae vīvere. (Fin. 4.41)
That is to live in conformity with nature.
[Cf. ūtī in the last example.]
Note 1— An infinitive may be used as direct object in connection with a predicate accusative (§ 393), or as appositive with such direct object.
Istuc ipsum nōn essecum fueris miserrimum putō. (Tusc. 1.12)
For I think this very thing most wretched, not to be when one has been.
[Here istuc ipsum belongs to the noun nōn esse.]
Miserārī, invidēre, gestīre, laetārī, haec omnia morbōs Graecī appellant (id. 3.7)
To feel pity, envy, desire, joy—all these things the Greeks call diseases.
[Here the infinitives are in apposition with haec]
Note 2— An appositive or predicate noun or adjective used with an Infinitive ín any of these constructions is put in the accusative, whether the infinitive has a subject expressed or not.
Nōn esse cupidum pecūnia est (Par. 51)
To be free from desires (not to be desirous) is money in hand.
[No subject accusative.]
a. The infinitive as subject is not common except with est and similar verbs. But sometimes, especially in poetry, it is used as the subject of verbs which are apparently more active in meaning.
Quōs omnīs eadem cupere, eadem ōdisse, eadem metuere, in ūnum coēgit. (Iug. 31)
All of whom the fact of desiring, hating, and fearing the same things has united into one.
Ingenuās didicisse fidēliter artīs ēmollit mōrēs. (Ov. P. 2.9.48)
Faithfully to have learned liberal arts softens the manners.
Posse loquī ēripitur. (Ov. M. 2.483)
The power of speech is taken away.
453. Rarely the infinitive is used exactly like the accusative of a noun.
Beātē vīvere aliī in aliō, vōs in voluptāte pōnitis. (Fin. 2.86)
A happy life different [philosophers] base on different things, you on pleasure.
Quam multa ... facimus causā amīcōrum, precārī ab indīgnō, supplicāre, etc.(Lael. 57)
How many things we do for our friends' sake, ask favors from an unworthy person, resort to entreaty, etc.
Nihil explōrātum habeās, nē amāre quidem aut amārī. (id. 97)
You have nothing assured, not even loving and being loved.
Note— Many complementary and other constructions approach a proper accusative use of the infinitive, but their development has been different from that of the examples above.
Avāritia ... superbiam, crūdēlitātem, deōs neglegere, omnia vēnālia habēre ēdocuit (Sall. Cat. 10)
Avarice taught pride, cruelty, to neglect the gods, and to hold everything at a price.