According to CosmeticsDesign-Europe, Yves Saint Laurent began developing Libre in 2011 and went through 1,570 versions before it launched in 2019. Perfumers Anne Flipo and Carlos Benaim built it as a lavender-based twist on the masculine fougere, which is a neat trick. Its first fragrance, Y, came out in 1964, and Opium in 1977 caused an argument over its name before anyone had smelled it.

That history is why a YSL eau de parfum is worth understanding before you buy one. The lineup is not one perfume, it is several families with a lot of spin-offs. Libre alone has a whole shelf, and Black Opium, which the Perfume Society dates to September 2014, has its own. Mon Paris arrived in June 2016 as a tribute to the 1983 fragrance Paris.

The first grid is Libre and Mon Paris, the floral side. The second is Black Opium, the coffee and vanilla side, and four scents from Le Vestiaire des Parfums, the house's wardrobe inspired by the couturier.

Here is a test I like: ignore the bottle and the version name, and ask what you want to smell like at six in the evening. Lavender and orange blossom, coffee and vanilla, or something woody and quiet. Then pick from that shelf.

Everything from Yves Saint Laurent in this grid rests on the same idea. The original Libre eau de parfum pairs French lavender with Moroccan orange blossom and musk accords, and the brand calls it bold and long-lasting. The rest are variations on that lavender and orange blossom core, so it helps to sort them by what got added.

For more warmth, there are three. Libre Intense adds glowing orchid and warm vanilla, and comes in a camel-colored bottle. Libre Le Parfum is the most concentrated and longest-lasting of the collection, according to the brand, with a saffron accord from the Ourika Community Gardens. Libre Vanille Couture is the sweetest, with Madagascar vanilla caviar that the brand says is hand-pollinated and cured over 18 months, plus rum absolute.

For something lighter, Libre Flowers & Flames goes sunkissed, with a coco-palm tree flower and lily accord. Libre Berry Crush is the fruit one, with raspberry and coconut around the same lavender. Libre Santal is a limited edition that adds New Caledonian sandalwood and tonka bean.

Mon Paris is a different mood entirely. It is a sweet floral with red berries, datura flower and patchouli, and the faceted, jewel-like bottle suits it.

A tip: if you already wear the original Libre and want a change, go one step warmer, not three. Intense or Santal is an easy move.

What I would skip: Libre Le Parfum in a hot room or on a summer commute. It is the richest of the group, so save it for evenings.

Black Opium is a different kind of Yves Saint Laurent. The original opens with black coffee and sweet vanilla and settles into white flowers, and the brand pitches it as a scent for an edgy, daring woman. Marie Salamagne is one of the four perfumers the Perfume Society credits with it.

The spin-offs are basically flavors. Black Opium Glitter goes fluffy, with marshmallow musk and a coffee accord, and the brand notes the perfume does not contain or spray glitter, only the bottle wears it. Over Red adds a cherry accord, with a dark red lacquered bottle to match. Pink Glaze brings in strawberry and jasmine over the coffee and vanilla, in a dark pink bottle.

Le Vestiaire des Parfums is a very different shelf. Babycat has pink pepper, black pepper and elemi, with saffron, vanilla, cedarwood and a suede accord. Tuxedo is violet leaf and bergamot on rose, lily of the valley, patchouli and vanilla bourbon. Blouse is the floral one, built on rose, with galbanum and pink pepper on top and musk and cashmeran below. Muse is a unisex scent with an ink accord, iris, and vanilla bourbon. Its perfumer, Marie Salamagne, is quoted in the description calling it a skin scent that explodes.

Here is a pairing I like: a Black Opium for nights out and one Vestiaire scent for the office, so you never have to pick one mood for the whole week.

What I would skip: wearing the Black Opium versions to a small meeting. They are meant to be noticed.

I think the honest way to shop YSL is to go by the family, not the newest bottle. If you like orange blossom and lavender, start with Libre. If you like a coffee shop, Black Opium. If you never liked either, the Vestiaire scents are the quieter room.

My rule: one spray on the wrist, one on a paper strip, and walk around for an hour before you decide. A scent that still pleases you after an hour is usually the right one. If you want to keep browsing, I also put together YSL Perfume and Prada Paradigme Eau de Parfum Starts With the Base and Works Up.