§405. Uses of the Ablative Proper

The Voluntary Agent after a passive verb is expressed by the Ablative with ā or ab:—

• laudātur ab hīs, culpātur ab illīs (Hor. S. 1.2.11), he is praised by these, blamed by those.
• ab animō tuō quidquid agitur id agitur ā tē (Tusc. 1.52), whatever is done by your soul is done by yourself.
• ā fīliīs in iūdicium vocātus est (Cat. M. 22), he was brought to trial by his sons.
• cum ā cūnctō cōnsessū plausus esset multiplex datus (id. 64), when great applause had been given by the whole audience.
• nē virtūs ab audāciā vincerētur (Sest. 92), that valor might not be overborne by audacity. [ Audācia is in a manner personified.]

a. The ablative of the agent with ab is sometimes used after intransitive verbs that have a passive sense:—

• perīre ab hoste, to be slain by an enemy.

b. The personal agent, when considered as instrument or means, is often expressed by per with the accusative, or by operā with a genitive or possessive:—

• ab explōrātōribus certior factus est (B. G. 1.21), he was informed by scouts (in person). But,—
• per explōrātōrēs Caesar certior factus est (id. 1.12), Cæsar was informed by (means of) scouts.
• ēlautae operā Neptūnī (Plaut. Rud. 699), washed clean by the services of Neptune.
• nōn meā operā ēvēnit (Ter. Hec. 228), it hasn't happened through me (by my exertions). [Cf. êius operā, B. G. 5.27.]

• equō vehī, to ride on horseback (be conveyed by means of a horse). [Not ab equō.]
• clipeōs ā mūribus esse dērōsōs (Div. 1.99), that the shields were gnawed by mice.

For the Dative of the Agent with the Gerundive, see § 374.

Ablative of Comparison