Passive Voice - Prepositions

Several prepositions can be used to indicate something about the action described in the passive voice. These are: the preposition for indicating the agent (von); for indicating the means (durch); and for indicating the instrument (mit).

Indicating the Agent

The agent of a sentence is the subject (a person or thing) who is actually carrying out the action. Take this example, where der Mann is the agent:

Der Mann isst den Apfel.

The man eats the apple.

Normally the agent is excluded when using the passive voice but it can be included via the preposition von.

Der Apfel wird von dem Mann gegessen.

The apple is being eaten by the man.

In administrative language, seitens (with genitive) is also a possibility:

Seitens der Behörde ist nichts unternommen worden.

Nothing has been done by the authorities.

The vast majority of passive sentences do not include an agent, so it can be eye-catching when it is included, drawing attention to itself as an important piece of information. Often the included agent is meant in a figurative sense:

Marco wurde von der Angst gehetzt, vor der Kamera zu versagen.
Marco was hounded by his fear of failing in front of the camera.

Indicating the Means

The means of a sentence, how the action was carried out, can be indicated via durch.

Ich wurde durch einen Boten benachrichtigt.

I was notified by messenger.

This also applies in the active voice.

Er benachrichtigte mich durch einen Boten.

He notified me by messenger.

Indicating the Instrument

The instrument or tool used to carry out an action is indicated via mit.

Das Glas wurde mit einem Hammer zerbrochen.

The glass was broken with a hammer.

This also applies in the active voice.

Der Junge zerbrach das Glas mit einem Hammer.

The boy broke the glass with a hammer.

Ambiguity of Usage: Durch or Von?

Sometimes you can argue that something serves the function of the agent and equally that of the means of an action. In such sentences, either von or durch can be used. For example:

Die Brücke wurde von Pionieren gesprengt.

Die Brücke wurde durch Pioniere gesprengt.
The bridge was blown up by sappers.