"To walk in Cambridge is often not a social experience at all, of course, but a sweet stretch of solitude and introspection. I weave through the neighborhood streets instinctively choosing the path that offers the greatest rewards that day: maximum leaf cover on a hot summer afternoon, fewest hills on the days when I'm weary, best front-yard crocuses on those first tentative days of spring. Unconsciously or consciously, I've charted this information onto my mental map of Cambridge, and I both draw upon it and update it as I walk. Even as my mind works over other matters — what to have for dinner, perhaps, or how to sort out a work-related dilemma — I find myself noting the human and natural goings-on around me: which tree's leaves are turning, who has a 'welcome home, baby' sign in their window, which cat has gone missing. Oddly, the combined activities of walking, observing, and internal musing often elicit my best thinking, as if considering new corners and perspectives outside has opened up new ones inside, too.

"When I walk, my pace is inarguably slower than it would be if I were driving, but it's also steady. There is none of the frustrating stop and go that drivers experience constantly in busy neighborhood streets. At heart, we all want freedom of movement, and like most people I can take great pleasure in cruising down an open road in a car, listening to music and watching the scenery pass by. But one doesn't find many open roads in the city (or anywhere else these days, for that matter). The prevalence of road rage around these parts is the clearest indication I know that car driving isn't giving people the sense of freedom they expect. But walking is different. You may have to pause, but you're never stuck. You move almost seamlessly through the city, with few blood-pressure raising surprises."