“Emotions are not just the fuel that powers the psychological mechanism of a reasoning creature,” philosopher Martha Nussbaum wrote in her masterful treatise on the intelligence of the motions, “they are parts, highly complex and messy parts, of this creature’s reasoning itself.” But the emotions and the intellect are just two parts of our creaturely trifecta of experience. The third, which can’t be disentwined from the other two and which is in constant dynamic dialogue with them, is the physical — the reality of the body.

More than a century before Nussbaum, the trailblazing psychologist William James (January 11, 1842–August 26, 1910) — who shaped our understanding of the psychology of habit — made a revolutionary case for “how much our mental life is knit up with our corporeal frame” in an 1884 essay titled “What is an Emotion?” included in The Heart of William James (public library).

Long before scientists came to demonstrate how our emotions affect our bodies, James argued that the relationship is bidirectional and that while “bodily disturbances” are conventionally considered byproducts or expressions of the so-called standard emotions — “surprise, curiosity, rapture, fear, anger, lust, greed, and the like” — these corporeal reverberations are actually the raw material of the emotion itself.

James writes:

Our natural way of thinking about these standard emotions is that the mental perception of some fact excites the mental affection called the emotion, and that this latter state of mind gives rise to the bodily expression. My thesis on the contrary is that the bodily changes follow directly the PERCEPTION of the exciting fact, and that our feeling of the same changes as they occur IS the emotion. Common sense says, we lose our fortune, are sorry and weep; we meet a bear, are frightened and run; we are insulted by a rival, are angry and strike. The hypothesis here to be defended says that this order of sequence is incorrect, that the one mental state is not immediately induced by the other, that the bodily manifestations must first be interposed between, and that the more rational statement is that we feel sorry because we cry, angry because we strike, afraid because we tremble, and not that we cry, strike, or tremble, because we are sorry, angry, or fearful, as the case may be. Without the bodily states following on the perception, the latter would be purely cognitive in form, pale, colourless, destitute of emotional warmth. We might then see the bear, and judge it best to run, receive the insult and deem it right to strike, but we could not actually feel afraid or angry.

The subtleties of our body language and physical instinct, James argues, are in concordance with the subtleties of our emotional experience:

No shade of emotion, however slight, should be without a bodily reverberation as unique, when taken in its totality, as is the mental mood itself. The immense number of parts modified in each emotion is what makes it so difficult for us to reproduce in cold blood the total and integral expression of any one of them. […] Our whole cubic capacity is sensibly alive; and each morsel of it contributes its pulsations of feeling, dim or sharp, pleasant, painful, or dubious, to that sense of personality that every one of us unfailingly carries with him.

Pointing out that we’re each familiar with the bodily experience of emotional states — the instinctual furrowing of the brow when troubled, the lump in the throat when anxious — James delivers the central point of his theory:

If we fancy some strong emotion, and then try to abstract from our consciousness of it all the feelings of its characteristic bodily symptoms, we find we have nothing left behind, no “mind-stuff” out of which the emotion can be constituted, and that a cold and neutral state of intellectual perception is all that remains. […] Can one fancy the state of rage and picture no ebullition of it in the chest, no flushing of the face, no dilatation of the nostrils, no clenching of the teeth, no impulse to vigorous action, but in their stead limp muscles, calm breathing, and a placid face? The present writer, for one, certainly cannot. The rage is as completely evaporated as the sensation of its so-called manifestations, and the only thing that can possibly be supposed to take its place is some cold-blooded and dispassionate judicial sentence, confined entirely to the intellectual realm, to the effect that a certain person or persons merit chastisement for their sins. In like manner of grief: what would it be without its tears, its sobs, its suffocation of the heart, its pang in the breast-bone? A feelingless cognition that certain circumstances are deplorable, and nothing more. Every passion in turn tells the same story. A purely disembodied human emotion is a nonentity.

It’s only in the past decade, more than a century after James developed his theory, that Western scientists have come to study this relationship through the field of embodied condition. But millennia-old Eastern traditions are built upon a foundational understanding of this osmotic interplay of flesh and feeling. Ancient mind-body practices like vipassana meditation are so effective because, in bringing us back into our bodies, they decondition our mental spinning and make us better able to simply observe our emotions as we experience them rather than being wound up and dominated by them.

Noting that his theory “grew out of fragmentary introspective observations,” James offers an empirical testament from his own interior life:

The more closely I scrutinise my states, the more persuaded I become, that whatever moods, affections, and passions I have, are in very truth constituted by, and made up of, those bodily changes we ordinarily call their expression or consequence; and the more it seems to me that if I were to become corporeally anaesthetic, I should be excluded from the life of the affections, harsh and tender alike, and drag out an existence of merely cognitive or intellectual form.

He notes that the purely cognitive experience of things is “more allied to a judgment of right than to anything else” — for instance, analyzing a symphony’s composition rather than letting the music, in the immortal words of Oliver Sacks, “pierce the heart directly.” Curiously, James argues that intellectual mastery of a specific domain blunts one’s ability to feel these physiological-aesthetic ripples of emotion:

Where long familiarity with a certain class of effects has blunted emotional sensibility thereto as much as it has sharpened the taste and judgment, we do get the intellectual emotion, if such it can be called, pure and undefiled. And the dryness of it, the paleness, the absence of all glow, as it may exist in a thoroughly expert critic’s mind, not only shows us what an altogether different thing it is from the “standard” emotions we considered first, but makes us suspect that almost the entire difference lies in the fact that the bodily sounding-board, vibrating in the one case, is in the other mute. “Not so very bad” is, in a person of consummate taste, apt to be the highest limit of approving expression.

The great physicist Richard Feynman, of course, vehemently disagreed. But James certainly had a point: I once knew a hard scientist, in every sense of the word, who very much embodied this withering of the expansive warmth of aesthetic appreciation in the grip of the cold intellect. On one occasion, she sent me a photograph from an autumn hike, depicting hills of trees covered in beautiful foliage at sunset. “Not bad,” she wrote.

James considers the interplay of these two faculties:

In every art, in every science, there is the keen perception of certain relations being right or not, and there is the emotional flush and thrill consequent thereupon. And these are two things, not one. In the former of them it is that experts and masters are at home. The latter accompaniments are bodily commotions that they may hardly feel, but that may be experienced in their fulness by Crétins and Philistines in whom the critical judgment is at its lowest ebb. The “marvels” of Science, about which so much edifying popular literature is written, are apt to be “caviare” to the men in the laboratories. Cognition and emotion are parted even in this last retreat, — who shall say that their antagonism may not just be one phase of the world-old struggle known as that between the spirit and the flesh? — a struggle in which it seems pretty certain that neither party will definitively drive the other off the field.

The essay, like every piece collected in The Heart of William James, is a magnificent read in its entirety. Complement it with James on choosing purpose over profit and the psychology of the second wind, then revisit immunologist Esther Sternberg on how our emotions affect our susceptibility to burnout and disease and Rilke on the relationship between the body and the soul.