Allen and Greenough's New Latin Grammar for Schools and Colleges
J. B. Greenough, G. L. Kittredge, A. A. Howard, Benj. L. D'Ooge, Ed.

[*] a. The infinitive is used in isolated passages instead of a subjunctive clause after habeō , dō, ministrō :—

tantum habeō pollicērī (Fam. 1.5A. 3), so much I have to promise. [Here the more formal construction would be quod pollicear .]
1. “ut Iovī bibere ministrāret ” (Tusc. 1.65) , to serve Jove with wine (to drink).
merīdiē bibere datō; (Cato R. R. 89), give (to) drink at noonday.

[*] b. Parātus , suētus , and their compounds, and a few other participles (used as adjectives), take the infinitive like the verbs from which they come:—

1. “id quod parātī sunt facere ” (Quint. 8) , that which they are ready to do.
2. “adsuēfactī superārī ” (B. G. 6.24) , used to being conquered.
currū succēdere suētī; (Aen. 3.541), used to being harnessed to the chariot
3. cōpiās bellāre cōnsuētās (B. Afr. 73), forces accustomed to fighting.

[*] Note.--In prose these words more commonly take the Gerund or Gerundive construction (§ 503 ff.) either in the genitive, the dative, or the accusative with ad :—

1. “īnsuētus nāvigandī ” (B. G. 5.6) , unused to making voyages.
2. “ alendīs līberīs suēti ” (Tac. Ann. 14.27) , accustomed to supporting children.
3. “corpora īnsuēta ad onera portanda ” (B. C. 1.78) , bodies unused to carry burdens.

[*] c. The poets and early writers often use the infinitive to express purpose when there is no analogy with any prose construction:—

1. “fīlius intrō iit vidēre quid agat ” (Ter. Hec. 345) , your son has gone in to see what he is doing. [In prose: the supine vīsum .]
2. “nōn ferrō Libycōs populāre Penātīs vēnimus ” (Aen. 1.527) , we have not come to lay waste with the sword the Libyan homes.
3. lōrīcam dōnat habēre virō; (id. 5.262), he gives the hero a breastplate to wear. [In prose: habendam .]

[*] Note.--So rarely in prose writers of the classic period.

For the Infinitive used instead of a Substantive Clause of Purpose, see § 457.

For tempus est abīre , see § 504. N. 2.

Peculiar Infinitives