[330]. The Infinitive with Subject Accusative (like the simple Infinitive) is used as Subject with esse and Impersonal verbs, particularly with aequum est, ūtile est, turpe est, fāma est, spēs est, fās est, nefās est, opus est, necesse est, oportet, cōnstat, praestat, licet, etc.; as,—
nihil in bellō oportet contemnī, nothing ought to be despised in war;
apertum est sibi quemque nātūrā esse cārum, it is manifest that by nature everybody is dear to himself.
B. As Object.
[331]. The Infinitive with Subject Accusative is used as Object after the following classes of verbs:
1. Most frequently after verbs of saying, thinking, knowing, perceiving, and the like (Verba Sentiendi et Dēclārandī). This is the regular construction of Principal Clauses of Indirect Discourse. Verbs that take this construction are, among others, the following: sentiō, audiō, videō, cognōscō; putō, jūdicō, spērō, cōnfīdō; sciō, meminī; dicō, affīrmō, negō (say that ... not), trādō, nārrō, fateor, respondeō, scrībō, prōmittō, glōrior. Also the phrases: certiōrem faciō (inform), memoriā teneō (remember), etc.
Examples:—
Epicūrēī putant cum corporibus simul animōs interīre, the Epicureans think that the soul perishes with the body;
Thalēs dīxit aquam esse initium rērum, Thales said that water was the first principle of the universe;
Dēmocritus negat quicquid esse sempiternum, Democritus says nothing is everlasting;
spērō eum ventūrum esse, I hope that he will come.
II. With jubeō, order, and vetō, forbid; as,—
Caesar mīlitēs pontem facere jussit, Caesar ordered the soldiers to make a bridge.
a. When the name of the person who is ordered or forbidden to do something is omitted, the Infinitive with jubeō and vetō is put in the Passive; as, Caesar pontem fierī jussit.