Guy de Maupassant notes in Bel Ami:
"The old woman in her turn kissed her daughter-in-law with hostile reserve. No, this was not the daughter-in-law of her dreams; the plumb, fresh housewife, rosy-cheeked like an apple and round like a brood mare. She looked like a hussy, the fine lady with her furbelows and her musk. For the old girl all perfumes were musk."In another story (One Evening) Maupassant attributes rather different connotations to musk:
"As for me, I was moved and powerfully interested, and in the darkness I could see that little woman, that little, fair, lively, artful woman, as if I had known her personally. I saw her selling her books, talking with the men whom her childish ways attracted, and in her delicate, doll-like head, I could see little crafty ideas, silly ideas, the dreams which a milliner smelling of musk attached to all heroes of romantic adventures".
Musk weaves its thick, ensnaring plot to even grace French roads with its sonorous name. In Greek the term "musk" is called μόσχος (MOS-chos) and it denotes (in both noun and verb form) any delightful aroma, from culinary to personal!
For all its rich history and ubiquity to the vernacular, musk remains a great mystery making even perfume lovers exasperate on its multiple facets and shady nature. Some, daunted by the odorant's sheer animal nature in some compositions such as Muscs Kublai Khan by Serge Lutens, reference "Post-coital genitals", "Caligula's couch", "balls' sweat", "the armpit of a camel driver who has not been near running water in a week" (the latter by Tania Sanchez in her early MUA days) and other highly entertaining descriptors. Kiehl's Original Musk, "wears its seductive intent on its sleeve" and Musc Ravageur tries to say it all at hello.
Those musks are generally termed "dirty" or "animalic musks", even "skanky" (both in reference to the little critter and the vulgar ladies thus called) in perfume-community-lingo; they tend to reflect the intimate aura of private parts and private acts and if you have any apprehension to smells that might offend your workplace or your conservative entourage, you might give them a miss. Nevertheless to a whole bunch of enthusiasts ~myself among them~ the smell is fur-like, cozy, intimate and transcedentaly primal. Not sweaty or fecal exactly, yet with a "lived-in" quality which is inescapeably delicious.
A vast array of different musks, termed "clean musks", are available for exploring for anyone afraid of the former, their scent often reminiscent of fabric softener, your laundry detergent or even shampoo and refined body powder. Serge Lutens has the polar opposite to Muscs Kublai Khan in Clair de Musc. Some of them often take the guise of "white musk", a code-name to signify a lightly floral musk "base", The Body Shop's White Musk being the most famous example. A reviewer at Fragrantica referring to Alyssa Ashley Musk (1969) notes:
"My perception of AA Musk is a very babylike, milky, powderish scent, completely non-defined by certain age or sex or the consumer."Perfect Veil by Creative Scentualisation, a combo of citrus, vanilla, sandalwood and musk, is termed "a casual, clean-smelling-skin scent" on Makeup Alley, a huge review site. Noa with its sparse formula is "fit for virgins and nuns" per Susan Irvine, a sentiment due to the transparent laundry-day white musks at its base. Allesandro del'Aqua and Helmut Lang make for a fascinating study in musk in their respective eponymous creations.
In some cases musks in a well-rounded composition manage to smell at once dirty and clean, like a human being in various stages of disarray. Such is the case with Chanel No.5: Its intense accord of ylang-ylang and musk, boosted by the soapy ppssshht of aldehydes (a group of predominantly synthetics that were used extensively in soaps and go well with musks) along with classical rose-jasmine, is the very core of sexy. Modern musky florals with woody bases such as Narciso For Her and Lovely by Sarah Jessica Parker utilize a cooler sensation, but with the same duality inherent. Imagine your dog and its own musky odor: Doesn't its true essence come out when just out of the shower?
But, herein lies the question, like a savvy member on Perfume of Life asked recently: "how on earth did musk, a term derived from the Sanskrit word for "testicles" because of its origins, come to be associated with cleanliness?"
What is musk in terms of smell and what accounts for its varied perception?
Musk of course originates from the Sanskrit muṣká meaning "testicle," coming as it did from the genital glands of the Musk Deer (moschus moschiferus); two pouches were extracted from the animal through cruel methods that resulted in its demise and the subsequent banning of the practice. The precious pods were opened to exude their aromatic effluvium, worth twice its weight in gold, and used as a powerful fixative and enhancer in perfumes & incense since antiquity. Musk odorants as a group however include glandular secretions from other animals as well, numerous plants emitting similar fragrances (ambrette seed being the most popular, highlighted beautifully in Musc Nomade by Isabelle Doyen for Goutal; also rosa moschata), and artificial substances with similar odors synthesized in the lab. But what perfumers refer to as "musk" is in realityits odorous principle, muscone (or muskone), or 3-methylcyclopentadecanone. Its chemical structure was first analysed by Lavoslav Ružička: Muscone is a 15-membered ring ketone with one methyl substituent in the 3rd position.
Still the fascinating reality is that human "reading" of musks differs widely. What is nectar to one can be anathema to another! Cast your mind back to Napoléon and Joséphine de Beauharnais: At the Directoire period the vogue for animalics (civet, musk, castoreum and ambergris) had given way to a new freshness, ushered in by the Revolution which stigmatised the "dirty" aromatics in relation to the decadent aristocrats who were guilotined. Only a defying elite, the Incroyables and Merveilleuses hung on to them, extravagant in style, wanting to emulate classical antiquity: Their nickname became les muscadins! Napoléon loathed musk and prefered to douse himself in Eau de Cologne and rosemary essence dilutions. His women, he preferred them in violets. The scorned Joséphine in an act of cunning revenge, when she was bypassed for another woman, doused her walls at Malmaison with her favourite musk essence, making her presence painfully unforgetable. Rumour had it that a hundred years later the scent was still perceptible! The Arabs knew a thing or two of musk's tremendous lasting power when they used crushed musk and rose in the mortar of their mosques so that the buildings would exude aromatic delight when warmed by the sun. But why the different reaction to musks?
The answer is twofold: Biological and psychological/cultural. In humans, odor perception phenotypes (MSHM1 and MSHM2) often account for specific hyperosmias (a heightened perception of odorants), the best studied examples being to musk and the sweaty odorant isovaleric acid. A great explanation why one's body odour might be inoffensive to one yet very repulsive/potent to another! Recent reseach going against established biology is that musk perception and sensitivity to it does not variate according to a woman's menstrual cycle like with some other odorants. Le Magnen in 1952 working with a dilution of Exaltolide (a synthetic musk) had found that women had significantly lower thresholds for it than men, 50% of the latter having difficulty in smelling it per se 
On the other hand, musk components (both natural and synthesized) are by their very nature very large molecules, bordeline undetactable due to that fact, making a large segment of the population anosmic (i.e.odor-blind) to some or other type. This is usually addressed by the perfume industry by employing an eventaille of various musk components of different molecular weights, so that if one doesn't click on the brain's receptor, another will. The most common anosmias are towards Androstenone (a sex pheromone possessing a musky facet) and Galaxolide (a very common synthetic "clean" musk), while there seems to be evidence of recessive inheritance for pentadecalactone sensitivity in humans; the inability to smell musk behaves as a recessive autosomal trait in a study of families.
The perception of any odorant however has to do with CONTEXT, as proven by the associations of wintergreen in the US vs the UK, "beach" scents and household products in different cultures. Ergo, it's largely cultural rather than biological. Real musk (the best is Tonquin) from musk deer has a rather urinous smell in itself with pungent, borderline fecal tonalities in its raw state, NOTHING like what you encounter in perfumes termed "musk" (even by top brands). Yet diluted and mixed with floral essences (try it with rose) it becomes a warm underground murmur of intimacy. A caress...
Historically, musk synthetics were used en masse in detergents and fabric softeners, roughly at the middle of the 20th century and onwards, to mask the more displeasing chemical nuances, due to their superb hydrophobic properties (ie. musks didn't wash off) and their low price (they were synthesized on the cheap). Thus the association of the "warm" smell of clean clothes out of the washing-machine as well as the lingering smell on the clothes themselves became an association with cleanness itself! That warm "cotton" feel you like in clean laundry? Musks! Funny for a product that initially signified the glandular secretion of a rutting deer's improper parts, isn't it? There is a pleiad of synthetic musk ingredients in the market, not just one or two types (on which we will revert in detail) and therefore there is no blanket term or description for them (not even "white musk" is sufficiently accurate), as every one of those molecules has a different olfactory profile: some smel "cleaner" like dryer sheets, some more metallic, some powdery even, others still with a fruity overlay, some have a vegetal or animalic quality. Hence the confusion of the consumer, who doesn't know what to expect from a "musky" fragrance (or reporting liking some in certain fragrances and detesting others to their puzzlement).
The popularity of said scented products led to the introduction of those functional musk notes in fine fragrance: The increasingly lower percentage of real natural musk in them, resulted in a paloply of "musks" which approximated the feeling of musk rather than the smell itself. Such musks were popular in the 70s especially (following the hippy movement, as a natural progression). The "dirty" association that several Baby Boomers have with musk is not exactly related to musk itself: Talking with American independent perfumer Dawn Spencer Hurwitz, she intelligently proposed that often the association is to the dense patchouli-clouds and unwashed parts (body odor) of the hippies of their youth, as the (incidental) added layer of musk oil was par for the course for the Woodstock era and beyond. The 1970s musks tagged their product with animal magnetism: "It's what attracts!" proclaimed a Jovan advertisement progressing well into the 80s and 90s.
Functional fragrance musks were incorporated in several other types of products as the years passed: soaps, shampoos, powders, deodorants, you name it! 99% of fine fragrances today contain some type of synthetic musk to anchor notes down, especially now that the other animalics are absent; this happens whether the note is "perceived" as musk or not and regardless of being stated as a note or not in the official descriptions. Since most of them fall under the "clean musks" umbrella ~and what's more under a screechy variant of them on top~, we can expect that generation Y will have no mental associations with any of the "skanky" musks and will come to regard the symbol (musk) as the collateral signification (laundry day) rather than the primal one (animal magnetism). The most interesting mental path of them all, nevertheless, is how the companies have incorporated the latter illusion in their ad copy without including the scent of it at all, rather opting for the equivalent of a line of warm cottons drying in the breeze. "Clean musks" are marketed as attractants, as powerful aphrodisiacs, as sexually inviting, thus equating "clean" with sexy! In a culture where personal grooming is a trillion dollar business it somehow logically follows.
Perhaps it was Charles Baudelaire who saw the duality of musk best: fresh yet intimate, and dedicated it to his "dearest, fairest woman" in his Hymn in Fleurs du Mal: "Sachet, ever fresh, that perfumes the atmosphere of a dear nook; Forgotten censer smoldering secretly through the night; Everlasting love, how can I Describe you truthfully? Grain of musk that lies unseen, in the depths of my eternity."
D.M.Stoddart, The scented ape: the biology and culture of human odour
translation William Aggeler, The Flowers of Evil (Fresno, CA: Academy Library Guild, 1954) Pics via wikimedia commons, parfum de pub, mongoose.wordpress.com, Nude Painting by Amedeo Modigliani via apolloart.com.
This is part of a series on the note of "musk" and its various types. Please also refer to: Part 2: Natural Deer Musk (Tonquin Musk), how does it smell and info on Synthetic Musk Substitutes and Part 3: The Many Permutations of Musk (Musk Types on the Market)