An active construction trains the reader’s gaze on someone who is doing something: See that lady with the shopping bag? She’s pelting a mime with zucchini. The passive trains the reader’s gaze on someone who’s having something done to him: See that mime? He’s being pelted with zucchini by the lady with the shopping bag. Using the wrong voice can make the reader crane back and forth like a spectator at a tennis match: See that lady with the shopping bag? A mime is being pelted with zucchini by her.
