Cold water and bare feet

In the 1820s a farmer's son in the mountains of Silesia named Vincenz Priessnitz healed his own broken ribs with cold wet compresses, and then built a clinic that treated thousands of people with nothing but cold water, fresh air, exercise and plain food. The nature cure. Sixty years later a Bavarian priest named Sebastian Kneipp, who'd cured his own tuberculosis by bathing in the icy Danube, wrote My Water Cure and systematized it: cold water applications, barefoot walking on wet grass and snow, herbs, simple food, and a balanced life. Kneipp spas still operate across Germany, and his five pillars are taught in medical schools there.

I'll be careful here. Nature cure, pushed to its extremes, has included claims that no serious person should accept, and nothing in this letter is a substitute for medicine. But the core of Priessnitz and Kneipp has aged remarkably well. Cold water, which you met on day forty-two, trains the stress response. Barefoot walking, which you did on day one, wakes up the feet and the balance. Fresh air, sunlight, movement and unprocessed food are now, two centuries later, the consensus of every public-health body on earth.

The key is the system. Kneipp didn't prescribe cold water alone, or herbs alone. He prescribed a way of living, five things together, and he said the healing was in the whole. That's the oldest form of what this year is: not one fix, but a life arranged so the body can do what it already knows how to do.

Kneipp's barefoot walk on wet grass is the practice I'd keep, because it costs nothing and does something: the cold on the feet, the uneven ground, the five minutes of attention to where you're stepping.