I'm holding a bowl of dirt up to my nose, in hopes of getting high on the fumes of my backyard compost pile. The microbe that I'm after today is M. vaccae, a living creature that acts like a mind-altering drug once it enters the human body. It has been shown to boost the levels of serotonin and norepinephrine circulating in the systems of both humans and mice. In other words, it works in much the same manner as antidepressant pills. And yes, it is possible to dose yourself by simply breathing in the smell of good dirt.

The drug-like effects of this soil bacteria were discovered, quite by accident, about a decade ago. A doctor named Mary O'Brien created a serum out of the bacteria and gave it to lung-cancer patients, in hopes that it might boost their immune systems. Instead, she noticed another effect: The hospital patients perked up. They reported feeling happier and suffered from less pain than the patients who did not receive doses of bacteria. Further studies in mice confirmed the mood-boosting effect of the soil bugs.

So now I'm poking at the dirt in this dish, trying to release as much of the M. vaccae as I can. The compost looks like chocolate cake -- it's a rich brown-black color, and it holds together with that same kind of moistness that we love in baked goods. I'm eager for something to make me feel jaunty on this winter day. Outside, the sky glimmers a dim, silver-gray -- it's filled with clouds that Virginia Woolf would have described as "implacable." I have always been sensitive to such days. The dishwater light trickles through the window and infects me with malaise.