We’re weekend walkers. We put our walking shoes on and catch the train out of the city with a thermos of tea and a baguette sticking out of one of our backpacks. We leave from one of the city’s five long-distance stations in shiny new suburban trains through a vast and tangled web of tracks. They weave in and out of each other like ribbons as we sway by, beaded here and there with discarded and graffitied wagons.

Taking the train is like going behind the scenes in your own city. Mostly, you realize that people live in places you would never imagine: a tiny, extra knob of concrete with a single window on the back of a five-story building; an abandoned house with no glass left in the windows; a mini shanty town on the steep bank of the railway itself, each hut surrounded by a vegetable garden. It’s always the drying laundry that gives the inhabitants away.

Judging Paris from inside its traditional walls, you could easily think it was static – a perfectly preserved urban artifact from pre-industrial France. But Paris is a city in development. This is visible leaving in any direction – biking across the Seine in the southeast towards the Bois de Vincennes on Sundays to play baseball, in the southwest by our climbing gym, from the train going northeast to Meaux and northwest towards Poissy. Half-built modern eco-neighborhoods composed of buildings apparently in design competitions to be the most austere or the least straight, drooling with three-story-tall vines and dotted with playgrounds and planted walkways and cranes.

This is about transitions.

My favorite word in French is “lisière”. It means the place between the field and the forest, or between the path and the hedge. Places of transition like this can accommodate species from either habitat plus many of their own because of the specific microclimates that they sustain. In this way, species that we often think of as forest fruit like wild strawberries, raspberries and blackberries are really fruit of the lisière – thriving from both the extra sunlight and the protection of the nearby trees.

Sometimes we stay onboard our train for as much as an hour. In that case, when we step off, it’s into pristine villages of stone houses, planter boxes, fountains and thirteenth century churches. The farmhouses on the outskirts of the village turn seamlessly to fields and they to forests complete with hidden castles. But sometimes our train trip is shorter. We pass the construction zones, the state-assisted housing, the shared gardens and the middle-class suburban towns. But we stay close enough that the landscapes in which we begin our walks remain punctuated by reminders of the ten million people living just beyond. The city sends out its tendrils of urbanism in the form of freeways, high-speed trains and over-head jet plane landing paths. They cut through fields and forests in regions that were formerly far enough to house the vacation homes of the Parisian nobility.

On a recent walk, we ducked under a highway overpass sheltering mattresses and sleeping bags accounting for nighttime inhabitants in the dozens. Fifty meters away a large snail crossed a flower-lined country lane in the rain. Ten minutes from the freeway the roar of traffic dissolved into a total ecstasy of lakeside birdsong. The forest floor was carpeted in blue and white flowers. A bright green caterpillar cautioned us against eating it. A baby boar crashed through the undergrowth. Later, we emerged from a thicket of equal parts trees and plastic lawn chairs to cross a train station. From the highway bridge above the tracks, we turned to look back at the distance we had covered; a sex-worker in white, thigh-high, lace-up, stiletto boots stepped out from the trees.

These landscapes are transition zones too. They are the giant lisière between the city and the country. The dregs of urban bustle and the strange outer-city human livelihoods merge with equally vigorous natural ecosystems where wild folk of all sorts abound. Passing through them often feels stressful, like an extra, frustrating obstacle between us and the freedom we seek among wild things. I try to tell myself that our walk doesn’t actually start until after the freeway and the homeless people, and that the sex-workers and the lawn chairs don’t count

It’s easy to represent the world in our imagination as if only old Paris and pristine villages existed. And yet it feels worth it, to me, to pay attention to the transition spaces between them. They too are real, stand-alone places with their own residents and industries; their tenants, unable to survive in either nature or society yet benefiting from both, live precisely at the confluence of the two worlds. They’re also proof that good quality nature, itself undiscriminating, isn’t confined to distant national parks. It thrives anywhere, and is beautiful even when it laps at concrete.

I suspect there might be lessons to be had… somewhere in the discovery of these places. Perhaps it is that they can only truly be witnessed on foot. Walking, we are of the same scale and move at the same speed as all of their elements… If anything, it is that they exist, and that they feel special enough to ponder and recount.

And so I do. These are the lives lived and the creatures seen in the in-between. This is the extra, oft-forgotten world into which one goes… walking on the margin.