One would be hard put to find just about anywhere an English grammar or composition textbook that did not take up the topic of what is called the passive voice of a verb. We are warned regularly and rightly to prefer the active to the passive, but as with all such exhortations, there are consequential exceptions. Hence the importance of the topic.
Imagine it is a completely beautiful summer day and you decide to go for a walk. You come upon a person holding a dog by the collar, and she explains that she found the animal lost in the nearby woods. In relating this incident to someone later, would it be better to say that the woman rescued the dog, or that the dog was rescued by the woman? Or imagine that instead of going for a walk, you decide to look at your mail and there you discover a bill for your property tax. Has the county raised property taxes again or were property taxes raised by the county again?
We know that every clause we construct combines a subject with a verb. These two elements, subject and verb, together compose the essential outline of action to which we want to draw the reader’s attention. If the subject we put down is actually undertaking the action of the verb—the woman rescued or the county raised, then that subject is called the agent of the verb. And when a verb has an agent, that verb is said to be in the active voice. The term agent derives from the Latin verb agere, to do. So active verbs have agents because they have doers.
If, however, the subject we attach to the verb is not the agent of the action, the verb is said to be in the passive voice. In saying the dog was rescued, you’re not saying the dog did anything; your intention, in fact, is precisely the opposite: you want the attention to fall on the hapless dog, not on the merciful passerby. Likewise, to say that property taxes were raised again is to cast the light on the situation you find yourself in, not on who is responsible for bringing that situation about.
And it is just because of this idea of responsibility that so much is made, and rightly so, of preferring the active voice to the passive. Those who are deft and facile with language know how to shift the burden of thinking to the reader or listener, a quick trick easily rendered when we remember that the passive construction is often acceptable without its prepositional phrase: property taxes were raised again. Truncating passive sentences like this, the rhetorical finagler has conveniently forgotten to include the prepositional phrase, where the agent could, albeit furtively, appear: property taxes were raised again by the county.
Having said all that, there is an important qualification to note about the passive voice. If that kindhearted passerby had found the dog injured and said he might have been hit by a car, that passive verb would be in order because the agent here, the car, is an inanimate object—without life and therefore without intention. To insist on the active voice, a car might have hit him, would be to place an unnecessary logical burden on the reader, attributing will to what doesn’t have a mind and so befogging an otherwise clear and present picture.
Because the verb stands as the center of gravity of a statement, it organizes the other elements of its clause. The voice of the verb will determine the perspective from which the reader sees what we’re trying to say. If the subject of the verb is an agent, we know who is doing something and we are telling the reader to keep that agent in mind as the sentence unfolds. If instead the subject is not an agent, then we are wanting the reader not to consider who is doing what—either because the agent is truly less important, or because we would prefer no one mention—or even think about–who did what to whom.