Heavy Construction

The Allen and Greenough is still under construction; so some links may not work quite the way you would expect.

Ablative of Agent.


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

NOTE 1: This construction is developed from the Ablative of Source. The agent is conceived as the source or author of the action.

NOTE 2: The ablative of the agent (which requires á or ab) must be carefully distinguished from the ablative of instrument, which has no preposition (§400). Thus - occísus gladió, slain by a sword; but, occísus ab hoste, slain by an enemy.

NOTE 3: The ablative of the agent is commonest with nouns denoting persons, but it occurs also with names of things or qualities when these are conceived as performing an action and so are partly or wholly persomfied, as in the last example under the rule.

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

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

NOTE 1: The ablative of means or instrument is often used instead of the ablative of agent, especially in military phrases: as, - haec excubitóribus tenébantur (B. G. vii. 69), these (redoubts) were held by means of sentinels.

NOTE 2: An animal is sometimes regarded as the means or instrument, sometimes as the agent. Hence both the simple ablative and the ablative with ab occur: -

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