Answering this question, I recalled a somewhat rare construction used to express that an action is characteristic of someone. Pekkanen's Ars Grammatica (§77.1) gives two examples:

  1. Cuiusvis hominis est errare, nullius nisi insipientis est in errore perseverare.
  2. Adulescentis est maiores natu revereri.1

I tried looking this up in online Latin grammars to provide a reference, but I failed to find anything. Can someone find an online Latin grammar that discusses this use of genitive and infinitive?

I am not aware of a specific name for this, so it is hard to search. Pekkanen lists it as a subclass of genetivus possessivus, but such classification is a somewhat arbitrary choice.

1 If you are puzzled by the word natu, see this follow-up question.


2 Answers 2


Allen & Greenough §343 also lists it as a type of possessive genitive, giving a few examples. Note that this use of the genitive in the predicate is used with infinitives and with clauses:

c. An infinitive or a clause, when used as a noun, is often limited by a genitive in the predicate:—

neque suī iūdicī [erat] discernere (B. C. 1.35), nor was it for his judgment to decide (nor did it belong to his judgment).

cûiusvīs hominis est errāre (Phil. 12.5), it is any man's [liability] to err.

negāvit mōris esse Graecōrum, ut in convīviō virōrum accumberent mulierēs (Verr. 2.1.66), he said it was not the custom of the Greeks for women to appear as guests (recline) at the banquets of men.

sed timidī est optāre necem (Ov. M. 4.115), but't is the coward's part to wish for death.

stultī erat spērāre, suādēre impudentis (Phil. 2.23), it was folly (the part of a fool) to hope, effrontery to urge.

sapientis est pauca loquī, it is wise (the part of a wise man) to say little. [Not sapiēns (neuter) est, etc.]

Note 1— This construction is regular with adjectives of the third declension instead of the neuter nominative (see the last two examples).

Note 2— A derivative or possessive adjective may be used for the genitive in this construction, and must be used for the genitive of a personal pronoun:—

mentīrī nōn est meum [not meī], it is not for me to lie.

hūmānum [for hominis] est errāre, it is man's nature to err (to err is human).

  • My favorite example is A.E.I.O.U. Austriae est imperare orbi universo. Jun 26, 2019 at 19:36

Is this predicative genitive + esse?

"est boni imperatoris bene ducere" = "It is of a good general to lead well.";

"est digni civis patriae cogitare" = "it is of a worthy citizen to think about his country.";

"est honesti regis regere sapienter" = "It is of an honourable king to rule wisely.";

"est canis feles agitare" = "It is of a dog to chase cats."

  • This is precisely the thing, thanks! Did you find a place where it's discussed?
    – Joonas Ilmavirta
    Jun 26, 2019 at 16:54
  • @Joonas llmavirta: net: "predicative gen. + esse".
    – tony
    Jun 27, 2019 at 8:32
  • @Joons llmavirta: In the 3rd ex., have changed "honest" to "honourable", which is more like it.
    – tony
    Jun 27, 2019 at 9:19

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