Walking, ideally, is a state in which the mind, the body, and the world are aligned, as though they were three characters finally in conversation together, three notes suddenly making a chord. Walking allows us to be in our bodies and in the world without being made busy by them. It leaves us free to think without being wholly lost in our thoughts.
I wasn't sure whether I was too soon or too late for the purple lupine that can be so spectacular in these headlands, but milkmaids were growing on the shady side of the road on the way to the trail, and they recalled the hillsides of my childhood that first bloomed every year with an extravagance of these white flowers. Black butterflies fluttered around me, tossed along by wind and wings, and they called up another era of my past. Moving on foot seems to make it easier to move in time; the mind wanders from plans to recollections to observations.
The rhythm of walking generates a kind of rhythm of thinking, and the passage through a landscape echoes or stimulates the passage through a series of thoughts. This creates an odd consonance between internal and external passage, one that suggests that the mind is also a landscape of sorts and that walking is one way to traverse it. A new thought often seems like a feature of the landscape that was there all along, as though thinking were traveling rather than making. And so one aspect of the history of walking is the history of thinking made concrete—for the motions of the mind cannot be traced, but those of the feet can.
Walking can also be imagined as a visual activity, every walk a tour leisurely enough both to see and to think over the sights, to assimilate the new into the known. Perhaps this is where walking's peculiar utility for thinkers comes from. The surprises, liberations, and clarifications of travel can sometimes be garnered by going around the block as well as going around the world, and walking travels both near and far.
Or perhaps walking should be called movement, not travel, for one can walk in circles or travel around the world immobilized in a seat, and a certain kind of wanderlust can only be assuaged by the acts of the body itself in motion, not the motion of the car, boat, or plane. It is the movement as well as the sights going by that seems to make things happen in the mind, and this is what makes walking ambiguous and endlessly fertile: it is both means and end, travel and destination.
-- Rebecca Solnit, from "Wanderlust: A History of Walking"