Whenever you’re reading old cocktail books, you’ll notice their authors don’t speak of vermouth in the same way we do. There’s no dry and sweet vermouth; there’s French and Italian vermouth. The reason for this is that through the middle of the 1800s, there was a Kingdom of Sardinia (known to us now only by the island of that name) whose mainland spanned the Alps—what is now France to the west, and what is now Italy to the east.
The Sardinians invented the aperitif, of which vermouth (named for wormwood, its primary botanical) is one. The aperitif, to the Sardinians, served many purposes. First, it gave them something to do with their excess wine (difficult to imagine such a thing, I know). It was also an ideal vehicle for local herbs and natural medicines—the alcohol in the wine stabilized the herbs and medicinal roots for shipment and trade. Soon enough, though, convalescents discovered that their medicine was also delicious. The word aperitif is a French derivation of the Latin verb aperire, which means “to open.” Aperitifs are intended to be drunk before a meal, to encourage the manufacture of gastric fluids and to stimulate appetite.
There’s a bit of evolutionary biology that applies to this phenomenon: We have been trained, for generation after generation from Adam down, to avoid bitter-tasting things because they might be poisonous. It’s why some people don’t like kale or Campari. It’s partly why children are particularly sensitive to bitterness and particularly prefer sweet things—our entire history as a species cries out against bitterness. As such, when we ingest something bitter, our stomachs downshift, producing more gastric juices, and our mouths produce more saliva, so as to expedite, if necessary, the immediate expulsion of a toxic substance.
This increased production of digestive fluids has the additional effect of settling our stomach and relieving the uncomfortable bloat of a big meal. Amari and other digestifs, taken after a meal, are a countervailing force to the essential immoderation of a good meal. Aperitifs, taken before a meal, enact the same digestive overdrive. The wormwood in vermouth in particular is so bitter that it gets the juices flowing with remarkable celerity. This is why a martini (a real martini, with at least ¾ of an ounce of good dry vermouth) or a manhattan before every meal is not only a good idea, but also an absolute necessity.
The reason why cocktailers in the Old Books came to refer to all dry vermouths as French and all sweet vermouths as Italian eludes easy explanation. The vermouths made on the west side of the Alps, in Chambéry, come in both sweet and dry varieties. And while Turin, on the east side of the Alps, is known mostly for its red, sweet vermouths (Martini & Rossi, Cinzano, and Cocchi are all based in Turin), many of those producers make dry vermouths as well (Martini & Rossi Extra Dry was introduced in 1900).
Both red and white wines are produced in both regions. No single botanical seems to be absolutely indigenous to either region, either. In all likelihood, the answer lies with the infinite recursion of market economics: Martini & Rossi happened to be the biggest producer of sweet vermouth when the American market opened up to it in the late 19th century, during the Golden Age of American drinking; likewise, Noilly Prat, in Marseilles, was the biggest dry vermouth producer of the era. They were the first to go to the American market with those respective products and to Americans, both were equally exotic. Hence, French Vermouth is dry, and Italian Vermouth is sweet.
Vermouth is vitally important to the history of the cocktail, and good vermouth is invaluable to a good drink. A few things to consider:
Putting as little vermouth as possible in your martini is not indicative of your drinking prowess or your manliness or womanliness. It is simply your insistence on drinking a terrible cocktail. Imagine taking the same attitude towards the manhattan (whose classic recipe maintains similar proportions to a real martini): “just a whisper of sweet vermouth.” “ . . . Very good, sir, 3 ounces of bourbon and bitters.” That is a terrible drink. Same with the martini. 2.5 ounces Plymouth gin, 0.75 to 1 ounce Noilly Prat Extra Dry, maybe a dash of orange bitters, twist, or olives. Stir it to an arctic temperature and tell me it isn’t a revelation.
Always keep your vermouth, both sweet and dry, in the refrigerator, and if it’s sat for more than a month, buy a new bottle. Think of it like a bottle of wine (because that’s effectively what it is): a dusty bottle can be delicious, just as long as it hasn’t been decorked.
Treat your vermouth well, trust it, use it with great abandon, and see how your life, like the Sardinians of old, will prosper.