In her novel Regeneration, Pat Barker writes of a doctor who 'knew only too well how often the early stages of change or cure may mimic deterioration. Cut a chrysalis open, and you will find a rotting caterpillar. What you will never find is that mythical creature, half caterpillar, half butterfly, a fit emblem of the human soul, for those whose cast of mind leads them to seek such emblems. No, the process of transformation consists almost entirely of decay.
They are all beasts of burden in a sense, ' Thoreau once remarked of animals, 'made to carry some portion of our thoughts.' Animals are the old language of the imagination; one of the ten thousand tragedies of their disappearance would be a silencing of this speech.
Perhaps walking is best imagined as an 'indicator species,' to use an ecologist's term. An indicator species signifies the health of an ecosystem, and its endangerment or diminishment can be an early warning sign of systemic trouble. Walking is an indicator species for various kinds of freedom and pleasures: free time, free and alluring space, and unhindered bodies.