One researcher combed three hundred childhood memoirs for a single pattern

In 1977, after years of unhurried, unfunded research, a former social worker named Edith Cobb published a book called The Ecology of Imagination in Childhood. She had spent decades watching children play and reading through some three hundred autobiographies written by creative adults, scientists, artists, poets, from a wide range of cultures and eras, looking for a pattern in how they described their own childhoods. She found one. Almost all of them, when they wrote about the roots of their own inventiveness, pointed back to an intense, sensory experience of the natural world in what she called the middle years of childhood: a stump climbed, a field lain in, a creek explored for hours.

Cobb's work, later refined by environmental psychologist Louise Chawla, connects to an idea developed separately by the Cambridge architect Simon Nicholson, who argued that everybody is naturally creative, but that modern life suppresses that instinct while treating a small elite of professional artists as the only people allowed to have it. Nicholson called his alternative the loose-parts theory: in any environment, he wrote, the degree of inventiveness and discovery available is directly proportional to the number and kind of variable, combinable elements in it. A swing set offers exactly one use. A pile of sticks, water, mud and long grass offers an almost unlimited number, because a child can combine them however imagination demands.

Landscape architect Robin Moore has taken this into direct comparison. Studies in Sweden found that children on flat asphalt playgrounds played in short, constantly interrupted bursts, while children in green, natural play areas built entire ongoing sagas that carried from one day to the next. In Denmark, children who spent their whole school day outdoors, whatever the weather, were more likely to invent their own games than children in a traditional kindergarten, and their social standing shifted too: leadership depended less on who was physically strongest and more on who was most imaginative.

Louv notes a specific irony here. Even a computer, with its near-infinite coding possibilities, is built from just two loose parts, a one and a zero. Nature, engaging every sense at once, still offers a richer box of parts than any screen has managed to match.

Stock one corner of the house or yard with loose, open-ended materials, sticks, stones, water, sand, scraps of cloth, rather than only single-purpose toys. Given the choice, pick the overgrown lot over the manicured playground, because uneven, textured ground invites longer and stranger play than flat asphalt ever does. When a fort or a leaf-and-twig shop appears, let it stay standing for a few days instead of tidying it away each evening, so the story it's part of has somewhere to continue. And once it's underway, step back; resist the urge to explain what the sticks are supposed to be.