On our daily 10-minute walk to my son?s school in Toronto?s west end, we pass a number of familiar sights: a couple of small dogs (a Boston terrier named Happ and a chihuahua named Milo); a grubby parkette littered with ancient, sun-bleached toys; the malodorous dumpster behind the seafood shop; the somewhat less malodorous dumpster behind the bustling microbrewery; and the railroad tracks where we sometimes pause to watch black train cars, each containing crude oil, slowly snake by. 
Recently, though, we passed something that my six-year-old son, Jack, had never really noticed before, or at least something he had never remarked on: someone smoking a cigarette. It was outside the fish store. Jack stared for a few moments and then muttered, just loud enough that the guy smoking could hear, ?That?s bad for the earth.? We kept walking, but I looked back to see the guy?possibly chastened, possibly just annoyed at this sanctimonious kid?toss his butt into the street. Over the past few months, ?That?s bad for the earth? has become a common refrain for Jack. Plastic: bad for the earth. Littering: bad for the earth. Driving: bad for the earth. Eating meat: bad for the earth and bad for animals. Listening to his teachers or classmates or just picking up on conversations at home had unleashed Jack?s environmental awareness, and it seemed to be boundless. Well, not quite: If you take him to a birthday party, he will still gleefully grab his loot bag, no matter how much disposable pla...