In 1724, in London, an instrument maker from Danzig named Daniel Gabriel Fahrenheit described his temperature scale in the Royal Society's Philosophical Transactions and was elected a Fellow the same year. A decade earlier, in 1714, he had made the first successful mercury-in-glass thermometers. Glass, mercury and heat, turned into a number everybody could agree on. Dior borrowed the name in 1988 for a men's fragrance, and the borrowing still feels earned.

Dior Fahrenheit is the one I would hand to a man who says every cologne smells the same. Dior presents it as violet leaf, wood and leather, opened by Sicilian mandarin, and the brand links the leather note to the Russian leather of hussars' boots, tanned with birch bark and recreated with birch, styrax and cade. The fragrance writer Persolaise called the 1988 original hyper-green, which is the most useful two words I know for it. The bottle has its own story. Dior says the fiery yellow-to-red gradient began as a cooling flaw in the glass at Saint-Gobain, and the house then built a dedicated furnace to reproduce it. A mistake, kept on purpose.

The trick with this first grid is to read it as a family tree. Start with Fahrenheit Eau de Toilette, the reference point. Fahrenheit Parfum is the richer reading of the same idea, so check the label to see which formula you are getting. Homme Parfum and the Homme Cologne Eau de Toilette Collection sit in the same house but speak more quietly. Sauvage Eau de Toilette and Sauvage Parfum are the ones your friends will recognise, Eau Sauvage is the old-school cologne shape, and Homme Sport is the one for a gym bag. Smell Fahrenheit first, then decide how far from it you want to travel.

Leather in a fragrance rarely smells like a jacket, and the quickest way to learn what you like is to spray three of these on paper strips, wave them dry and come back in an hour. The ones you keep sniffing are your answer.

Mugler's Cuir Impertinent is the one with the French word right in the name, and Montblanc's Collection Extreme Leather is the plain-spoken version. Tom Ford's Ombré Leather Parfum comes with amber and jasmine flower on the label, which tells you it leans soft and warm. Burberry's Hero Parfum Intense pairs cedarwood with a leather accord, Hugo Boss Bottled Beyond Intense adds orange to its leather, and Rabanne's 1 Million Eau de Toilette with Leather is the easiest, most wearable step in.

Viktor&Rolf's Spicebomb Dark Leather brings incense, and Dolce&Gabbana's K Eau de Parfum Intense puts fig beside its leather. Those two are the ones for a man who finds straight leather too severe.

A pairing I like: Fahrenheit by day, from the grid above, and one of these in the evening. Same idea, two volumes.

What I would skip: a dark leather scent on a hot afternoon commute. Leather wants cool air and a jacket.

Evening scents go wrong at the first spray, so use one spray fewer than you think you need and put it on before you get dressed. A bold fragrance should arrive a second after you do, not a minute before.

Tom Ford's Noir Extreme Parfum comes with sandalwood and saffron on the label, which is about as dressed up as a bottle gets. Gucci's Guilty Pour Homme Eau de Parfum and Jean Paul Gaultier's Le Beau Le Parfum make a pair for a man who wants a fragrance with a personality. Prada's Luna Rossa Black Eau de Parfum is the cooler, more tailored option.

Jean Paul Gaultier's Le Male Elixir pairs lavender with tonka bean, and Viktor&Rolf's Spicebomb Extreme goes for bourbon vanilla and tobacco, so that one is a winter bottle by nature. Armani Beauty has two here: Stronger With You Absolutely Parfum with rum and cedarwood, and Armani Code Parfum, which I would keep for dinners where someone else is cooking.

What I would skip: bourbon vanilla and tobacco in a small, warm restaurant. A scent that fills the room is a bad guest.

A shower gel that matches the scent you plan to wear makes a morning smell like one decision instead of three. It is the quietest upgrade in a men's routine.

Dior makes that easy, and it is why I like starting a routine from this end of the grid rather than the bottle. Fahrenheit Aftershave and Fahrenheit Shower Gel sit right beside the scent, and Sauvage has a Shower Gel and an After-Shave Balm of its own. The Homme Eau de Toilette Aftershave Balm is there for anyone who wants the house signature in a gentler, post-shave form.

Versace's Eros Flame Aftershave Lotion and Eros Aftershave Balm, plus Rabanne's Invictus After Shave Lotion, are the choices from outside Dior, and I would pick between lotion and balm by how your skin feels after the razor, not by the label.

I use the Fahrenheit shower gel first, then the aftershave on a freshly shaved jaw, and nothing else on the neck. Save the eau de toilette for the wrists. Less is more here, because the gel and the aftershave already carry the same accent.

What I would skip: layering three different scents in one morning. Pick a family and let it run.

I think Dior Fahrenheit deserves a proper smell, not a glance. It is a green, leathery scent with a story behind its bottle, and the current Eau de Toilette is, as Persolaise notes, different from the 1988 original, so judge it as it is today.

I would start with the Eau de Toilette, test one leather scent and one evening scent against it, and add the aftershave when the bottle becomes a habit. Daniel Gabriel Fahrenheit gave the world a number for heat. Dior gave men a way to wear it.

Fahrenheit asks you to smell it properly, and the easiest way to do that is against the other Dior bottles and a couple of rivals. Sauvage Eau Forte Parfum and Sauvage Extrait are the louder pair, Dior Homme Intense Eau de Parfum is the deeper one, and Homme Sport and the Eau Sauvage Cologne are the fresher choices. From other houses, I would test Dolce & Gabbana Light Blue Pour Homme, Gucci Guilty Elixir de Parfum and The One Pour Homme next. Then come the finishing touches: Jean Paul Gaultier Le Male Soothing Alcohol-Free After Shave Balm, the Chanel Allure Homme Sport After Shave Lotion and Tom Ford Neroli Portofino Hand & Body Moisturizer. Keep the aftershave plain and let Fahrenheit do the talking.