I'm interested in reading a series of the art and craft of writing by Constance Hale, a San Francisco-based journalist in the New York Times. The 4th in the series on NYT April 30 issue deals with the use of passive voice under the title, “The pleasures and perils of the passive," which reads as follows;
The word passive gets a bad rap. Maybe a high school teacher forbade “passive constructions.” Or we recall authorities like Strunk and White, who famously told us to “use the active voice.”
There is certainly some merit to this rule of thumb; some of the worst writing around suffers from inert verbs and the unintended use of the passive voice. Yet the passive voice remains an important arrow in the rhetorical quiver. After all, it exists for a reason.
I don't understand the line – "the passive voice 'remains an important arrow in the rhetorical quiver'" in the above quotation. I assume it's a metaphorical expression. Though it may sound like sour grapes, I think clarity is the best art and craft of writing preceding to any other techniques.
Can you explain the line in plainer English for me? Is "an important arrow in something" a well-used expression?