On Smell is a short essay by Lewis Thomas.  The essay was published in an anthology called The Bedford Reader (1985) and reposted online by the blogger Allisonian.


The vacuum cleaner turned on in the apartment’s back bedroom emits a high-pitched lament indistinguishable from the steam alarm on the teakettle in the kitchen, and the only way of judging whether to run to the stove is to consult one’s watch: there is a time of day for the vacuum cleaner, another time for the teakettle. The telephone in the guest bedroom sounds like the back-door bell, so you wait for the second or third ring before moving. There is a random crunching sound in the vicinity of the front door, resembling an assemblage of people excitedly taking off galoshes, but when listened to carefully it is recognizable as a negligible sound, needing no response, made by the ancient elevator machinery in the wall alongside the door.  So it goes.  We learn these things from day to day; no trick to it.

Sometimes the sounds around our lives become novel confusions, harder to sort out; the family was once given a talking crow named Byron for Christmas, and this animal imitated every nearby sound with such accuracy that the household was kept constantly on the fly, answering doors and telephones, oiling hinges, looking out the window for falling bodies, glancing into empty bathrooms for the sources of flushing.

We are not so easily misled by vision.  Most of the things before our eyes are plainly there, not mistakable for the other things except for the illusions created for pay by professional magicians and, sometimes, the look of the lights of downtown New York against a sky so black as to make it seem a near view of eternity. Our eyes are not easy to fool.

Smelling is another matter. I should think we might fairly gauge the future of biological science, centuries ahead, by estimating the time it will take to reach a complete, comprehensive understanding of odor.  It may not seem a profound enough problem to dominate all the life sciences, but it contains, piece by piece, all the mysteries.  Smoke: tobacco burning, coal smoke, wood-fire smoke, leaf smoke. Most of all, leaf smoke. This is the only odor I can will back to consciousness just by thinking about it. I can sit in a chair, thinking, and call up clearly to mind the smell of burning autumn leaves, coded and stored away somewhere in a temporal lobe, firing off explosive signals into every part of my right hemisphere. But nothing else: if I try to recall the thick smell of Edinburgh in winter, or the accidental burning of a plastic comb, or a rose, or a glass of wine, I cannot do this; I can get a clear picture of any face I feel like remembering, and I can hear whatever Beethoven quartet I want to recall, but except for the leaf bonfire I cannot really remember a smell in its absence. To be sure, I know the odor of cinnamon or juniper and can name such things with accuracy when they turn up in front of my nose, but I cannot imagine them into existence.

The act of smelling something, anything, is remarkably like the act of thinking itself. immediately, at the very moment of perception, you can feel the mind going to work, sending the odor around from place to place, setting off complex repertoires throughout the brain, polling one center after another for signs of recognition, old memories, connections. This is as it should be, I suppose, since the cells that do the smelling are themselves proper brain cells, the only neurones whose axones carry information picked up at first hand in the outside world. Instead of dendrites they have cilia, equipped with receptors for all sorts of chemical stimuli, and they are in some respects as mysterious as lymphocytes. There are reasons to believe that each of these neurones has its own specific class of receptors; like lymphocytes, each cell knows in advance what it is looking for; there are responder and nonresponder cells for different classes of odorant.  And they are also the only brain neurones that replicate themselves; the olfactory receptor cells of mice turn over about once every twenty-eight days. There may be room for a modified version of the clonal-selection theory to explain olfactory learning and adaptation. The olfactory receptors of mice can smell the difference between self and nonself, a discriminating gift coded by the same H-2 gene locus governing homograft rejection. One wonders whether lymphocytes in the mucosa may be carrying along this kind of genetic information to donate to new generations of olfactory receptor cells as they emerge from basal cells.

The most medically wonderful of all things about these brain cells is that they do not become infected, not very often anyway, despite their exposure to all the microorganisms in the world of the nose. These must exist, in the mucus secretions bathing this surface of the brain, the most extraordinary antibiotics, including eclectic antiviral substances of some sort.

If you are looking about for things to even out the disparity between the brains of ordinary animals and the great minds of ourselves, the superprimate humans, this apparatus is a good one to reflect on in humility. Compared to the common dot, of any rodent in the field, we are primitive, insensitive creatures, biological failures. Heave knows how much of the world we are missing.

I suppose if we tried we could improve ourselves. There are, after all, some among our species with special gifts for smelling — perfume makers, tea tasters, whiskey blenders — and it is said that these people can train themselves to higher and higher skill by practicing. Perhaps, instead of spending the resources of our huge cosmetic industry on chemicals for the disguising or outright destruction of odors we should be studying ways to enhance the smell of nature, facing up to the world.

In the meantime, we should be hanging on to some of the few great smells left to us, and I would vote for the preservation of leaf bonfires, by law if necessary. This one is pure pleasure, fetched like music intact out of numberless modular columns of neurones filled chockablock with all the natural details of childhood, firing off memories in every corner of the brain. An autumn curbside bonfire has everything needed for education: danger, surprise (you know in advance that if you poke the right part of the base of leaves with the right kind of stick, a blinding flare of heat and fragrance will follow instantly, but it is still an astonishment when it happens), risk, and victory over odds (if you jump across at precisely the right moment the flare and sparks will miss your pants), and above all the aroma of comradeship (if you smell that odor in the distance you know that there are friends somewhere in the next block, jumping and exulting in their leaves, maybe catching fire).

It was a mistake to change this, smoke or no smoke, carbon dioxide and the greenhouse effect or whatever; it was a loss to give up the burning of autumn leaves. Now, in our haste to protect the environment (which is us, when you get down to it), we rake them up and cram them into great black plastic bags, set out at the curb like wrapped corpses, carted away by the garbage truck to be buried somewhere or dumped in the sea or made into fuel or alcohol or whatever it is they do with autumn leaves these days. We should be giving them back to the children to burn.

— Lewis Thomas


1913–1993, American physician and biologist, b. Flushing, New York. In his youth he often accompanied his physician father on his rounds and decided early on to be a doctor or a writer. He graduated from Princeton, and obtained his medical degree from Harvard in 1937. He held various professorships and research posts and was dean of the medical schools of New York University (1966–69) and Yale (1972–73). He served as president (1973–80) then chancellor (1980–83) and president emeritus (from 1983) of Memorial Sloan-Kettering Cancer Center in New York City. He is mostly widely known, however, for his lucid essays that combine his fascination for the living world with his thoughts on biology and philosophy. His collections of his essays include The Lives of a Cell (1974), The Medusa and the Snail (1979), and Late Night Thoughts on Listening to Mahler’s Ninth Symphony (1983).