In the late nineteen-twenties, the physiologist Walter Cannon coined the term “homeostasis”—joining together the Greek homoios (similar) and stasis (stillness). The capacity to sustain internal constancy was an essential feature of an organism, he argued. His work was rooted in his experiences working with Allied troops during the First World War, as he studied the physiological complications of traumatic shock. But it was also inspired by the work of predecessors such as the nineteenth-century French physiologist Claude Bernard, who wrote, famously, “La fixité du milieu intérieur est la condition de la vie libre, indépendante”: the constancy of the interior environment is the condition of free and independent life.

“Constancy in an open system, such as our bodies represent, requires mechanisms that act to maintain this constancy,” Cannon wrote. “Homeostasis does not occur by chance, but is the result of organized self-government.”

Cannon’s insight inverted long-established logic. Physiologists, for generations, had described animals as assemblages of machines—as sums of dynamic parts. Muscles were motors; the heart a pump; the nerves electrical conduits. Pulsing, swivelling, pumping, sparking; the emphasis was on movement, on actions, on work—Don’t just stand there, do something. In shifting physiology’s focus from action to the maintenance of fixity, Cannon (and Bernard) had fundamentally changed our conception of how the human body works. A major point of physiological “activity,” paradoxically, was to enable stasis. Don’t just do something, stand there.

All around Cannon, theorists were thrilling to the idea of self-righting systems, resistant to the buffeting forces of change. The English botanist Arthur Tansley coined the word “ecosystem” in 1935; the maintenance of stability would soon be described as one of the cardinal properties of ecologies. Soon economists were relating homeostasis to self-correcting markets; Norbert Wiener, the mathematician, saw that machines and creatures might be governed by autonomous control systems stabilized by “feedback” loops. Cells, cities, societies, even political institutions—all had the capacity to steady their states through the actions of self-regulated and counterpoised forces. And Lewis Carroll’s Red Queen was their symbolic monarch. The world is spinning so fast under her feet, she tells Alice, that “it takes all the running you can do to keep in the same place.”