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Allen and Greenough/ New Latin Grammar

Ablative of Means or Instrument

411. Opus and ūsus, signifying need, take the Ablative:—1

magistrātibus opus est (Leg. 3.5), there is need of magistrates.

nunc vīribus ūsus (Aen. 8.441), now there is need of strength.

Note— The ablative with ūsus is not common in classic prose.

a. With opus the ablative of a perfect participle is often found, either agreeing with a noun or used as a neuter abstract noun:—

    opus est tuā exprōmptā malitiā atque astūtiā (Ter. And. 723), I must have your best cunning and cleverness set to work.

    properātō opus erat (cf. Mil. 49), there was need of haste.

Note 1— So rarely with ūsus in comedy: as, quid istīs ūsust cōnscrīptīs (Pl. Bacch. 749), what's the good of having them in writing?

Note 2— The omission of the noun gives rise to complex constructions: as, quid opus factōst (cf. B. G. 1.42), what must be done? [Cf. quid opus est fierī? with quō factō opus est?]

b. Opus is often found in the predicate, with the thing needed in the nominative as subject:—

dux nōbīs et auctor opus est (Fam. 2.6.4), we need a chief and responsible adviser (a chief, etc., is necessary for us).

sī quid ipsī opus esset (B. G. 1.34), if he himself wanted anything (if anything should be necessary for him).

quae opus sunt (Cato R. R. 14.3), things which are required.


XML File

This construction is properly an instrumental one, in which opus and ūsus mean work and service , and the ablative expresses that with which the work is performed or the service rendered. The noun ūsus follows the analogy of the verb ūtor , and the ablative with opus est appears to be an extension of that with ūsus est .