The Cramp I Thought Myself Into

Every New Year, someone wishes you 心想事成. It’s usually translated as “may all your wishes come true,” but the characters say something stranger: may what the heart thinks become a thing. I’ve always liked that version better, right up until the night before a big deadline, when what my heart is thinking turns into a knot just under my ribs. You probably know the one. Nothing is wrong with your stomach. You haven’t eaten anything bad. You’re just worried, and the worry has somehow become a cramp. The heart thought, and a thing happened. Just not the thing anyone wished for.

What gets me is how ordinary this is, because when you slow down and look at it, it shouldn’t be possible at all. A worry has no weight and no shape. It doesn’t take up space. A stomach is muscle and lining and nerves. So how does the first one squeeze the second?

This is an old question, and one of the sharpest people to ask it was twenty-four years old. René Descartes had argued that a person is made of two different kinds of thing: a body, which takes up space, and a mind, a “thinking substance” that doesn’t. In May 1643, Princess Elisabeth of Bohemia wrote to him and asked, in effect, how that could work. If the soul is only a thinking substance, how can it move the body’s spirits to produce a voluntary action? Something with no extension has nothing to push with. Descartes answered more than once, and in his last book, The Passions of the Soul (1649), he pointed to a small gland in the center of the brain as the place where mind and body meet. But a meeting place isn’t a mechanism, and Elisabeth’s question has outlived his answer.

Most people working on this today drop Descartes’s picture. The worry isn’t a ghost acting on the body from outside. It’s something the brain is doing, and the brain is wired to the gut very directly, most famously by the vagus nerve, which runs from the brainstem all the way down to the digestive tract. The physician Emeran Mayer, in a 2011 review in Nature Reviews Neuroscience, describes the brain and the gut as a two-way communication system: stress signals from the brain change how the gut moves and how sensitive it is to its own signals, and the gut sends signals back. I’ve written before about how my hands shake before a toast, and the stomach is part of the same wiring. The knot is real, then. It isn’t imagined.

It’s worth being careful about what stress doesn’t do, though. For a long time, people believed stress and stomach acid caused ulcers. Then Barry Marshall and Robin Warren showed that most ulcers come from a bacterium, Helicobacter pylori, and they won the 2005 Nobel Prize in Physiology or Medicine for it. Stress can make your stomach hurt. It just isn’t the whole story it was once thought to be, which is a good reminder of how easy it is to give a feeling more credit than it earned.

And that’s where the old question comes back in a new form. In Mind in a Physical World (1998), the philosopher Jaegwon Kim pressed a problem that makes Elisabeth’s look gentle. If every physical event has a complete physical cause, then the brain activity is enough, all by itself, to make your stomach knot. What’s left, then, for the worry, the felt thing, to do? Either the worry simply is that brain activity, in which case “my worry caused the cramp” is true but less mysterious than it sounds. Or the worry is something extra riding along on top of it, and then it doesn’t seem to do any work at all.

There’s one experiment I keep coming back to. In 1978, Jon Levine, Newton Gordon, and Howard Fields gave dental surgery patients a placebo after their wisdom teeth came out. Some of them felt less pain. Then the researchers gave them naloxone, a drug that blocks the receptors the body’s own painkillers work through, and for those patients the pain went up again. Believing the pill would help seems to have released real painkillers in their brains. Belief does something to the body, measurably. But notice how it does it: through chemistry, the same way everything else does. The placebo makes thought look powerful and ordinary at the same time.

So I don’t know what to say about the night before a deadline. Maybe the worry and the knot are two views of one event: from the inside, it’s dread, and from the outside, it’s nerves firing and muscles tightening. Or maybe the brain does the whole thing on its own, and the worry is just the part of it I happen to be able to feel, arriving a little after the cramp to tell me what’s going on. 心想事成, people say. What the heart thinks becomes a thing. I still can’t tell whether my heart did the thinking, or just found out about it.