If Charles James has a spiritual heir, it's Zac Posen. Both rose to fame when they were barely out of their teens, both lay claim to a high-society clientele (blue bloods for James, Hollywood celebrities for Posen), and both are famously known for a flamboyant sense of confidence. "I'm the most copied person in the world," James once declared. And this, from Posen: "I'm definitely planning ahead for a brand that spans the universe, a Zac Posen universe."

The most valuable lesson Posen picked up from James is not, however, his quippishness. Rather, it's the evocative way James draped fabric on the mannequin. "He took cut to its purest form," Posen says. "For me his work is always there." Here, Posen speaks with about James' "emotional engineering," why the Costume Institute's upcoming retrospective is good for American fashion, and, best of all, what he's wearing to the Met ball.

Let's start with the important stuff: What are you wearing to the Met ball?

Ralph Rucci is making me a couture piece. I've always been a fan of his work, and I've been working with Anna Cleveland for a very long time now, and he started working with her as his fit model. I asked him if he would ever be interested in making men's pieces, and he offered to make me something. I'm actually the second man he's made clothing for after André Leon Talley. We've had multiple toiles, multiple fittings. As a designer it's really interesting and I think probably very rare to have this experience. There are not many people who make custom couture anywhere in the world. It's made me very happy about fashion.

But does it follow the strict dress code that was announced earlier this month?

It's a piece inspired by James made by the designer who wrote the forward to the exhibition book—I think we get a pass. It's good to break rules in fashion.

Was Charles James a rule-breaker?

Yes, absolutely. He was a rule-breaker through form, through cut. To find construction methods through emotional building is rule-breaking. He found new ways to engineer fabric and cut; he was very interested in ideas of modernity at the time.

Do you remember falling in love with Charles James' work?

The first time Charles James came into my world was through René Ricard [the art critic], when I was 15 years old. At that point James was a fully forgotten designer. At that point fashion was rediscovering Madeleine Vionnet. It wasn't what was being emphasized behind the scenes at the Met during Richard Martin's time. When I was interning there, I saw a lot of Vionnet, Balenciaga, Gaultier.

I thought there was something very feminine about James' designs, as well as something technical and slightly futuristic that I was viscerally drawn to. The V&A Museum in London had James' quilted satin puffer jacket on display when I was a student at Central Saint Martins, and it was something that I was very drawn to. But otherwise there wasn't much material on him. There was no Google search at the time, it was library times. Much later, after design school, I met Paul Cavaco and Kezia Keeble's daughter Cayli and she brought me some of the cherished books of Kezia's, one of which was the James catalog from the Brooklyn Museum show, and it was incredibly transformative. It became a kind of bible in a way.

You mentioned Balenciaga. I see Balenciaga and Dior in these pieces, but according to what I've read, they both bowed down to James.

There are no gimmicks here. This is real-deal emotional engineering.

What does that term, "emotional engineering," mean?

When James is draping and constructing, he's three-dimensionally drawing on the body. This isn't coming from a sketch. The nuance of, say, taking fabric from a center back on the bias and pulling it around [the bust] and it just happens to beautifully, gesturally create a curve…those are sensual and emotional decisions, and those impromptu gestures when they're materialized, they become engineering feats. It's painterly, it's sculpted. He's not fudging it in with a tuck or a pleat or hiding fabric underneath.

He's highlighting the body throughout his work, contouring it and testing the confines of form. It's hard to keep the ease of an original gesture. With every step, something from the original gesture, the soul of it, gets taken out. It's very hard to keep that integrity. Probably the best living designers now with that integrity are Yohji Yamamoto and Vivienne Westwood. The cut of Westwood's clothing still has that direct emotional quality where you know she draped it on her little mannequin. James' clothing—obviously there's not often a lot of ease to it, but he's thinking totally three-dimensionally and you can't sketch three-dimensionally.

Regarding Westwood and Yamamoto, would you say that they were inspired by James?

I know they are. Also Alber [Elbaz of Lanvin]. In the most modern way of ready-to-wear, he's been able to achieve the gesture of James and of Balenciaga in his work, but with an aesthetic acceptance of the quick stitch. And, of course, Geoffrey Beene. In the famous Cecil Beaton image [that's on the cover of the catalog], there's historical frivolity. But as James and his contemporaries grew, his work got to a place of purity. And I think a lot of designers who are obsessed with cut and construction are obsessed with purity. Things that look simple are often harder to make.

Do you feel like you've absorbed any lessons from James?

Patience, perfection, trust of cut and fabric. I fell in love with Valerie Steele when she once took a Charles James dress from the FIT collection—it was on a dissection desk, and we laid out all the different layers of tulle. It was so extreme. You can see the layers and the cross-section in diagrams, different books of his work. As it grew out, the dress almost got less detailed—it's more detailed and ornate on the inside than the outside. Well, of course Cristobal Balenciaga liked it.

One thing you notice as the Met shows come and go is that many reverberate in fashion. In anticipation of last year's Punk show, a lot of designers went punk, for example. Do you think this show will have an effect on contemporary fashion?

No. It's too costly. James' dresses are more complicated than Bilbao [the Frank Gehry-designed Guggenheim museum]. Really. This is hard stuff to make and to do. It takes a trained atelier. This isn't clothing that fits into the system of how a lot of designers work today. Remember, what James did is not ready-to-wear. There's a humanistic make to his dresses that I think makes them charming. You can see the hand, and I love that.

Was André Leon Talley the first person to compare you to James?

Yes, André. Our first show at the tents [for Fall ’04], we had these silver trees and we had a series of pieces with a Jamesian pintucking technique. I think André wrote a piece when I was making one of the finale gowns for that show that it was like watching James in the studio. And then I started making more extravagant pieces, when I had the resources to start building and pushing my patternmakers to the limit, René Ricard did as well.

What did it feel like to be compared to James?

It was a huge honor. I probably didn't understand what a level of honor it was. He was a forgotten designer at the time. Sometimes it takes years after their death for the collective to see the impact of a great designer's work. Today, we live in a world where things are references of a reference. We're in the Instagram repost age. These are originals. When I see this stuff I think, Oh, I would love to just focus on one-of-a-kind pieces and put less waste in the world. You know, there's so much product in the world. Why can't people put their energies and work to making pieces that reach this level of perfection?

We wouldn't be able to afford them!

That's true. It's a huge deal that the Met is celebrating an American creator and couturier. Sportswear and lifestyle is what American fashion is, what it's known for, but with James you're seeing someone who was dedicated at such a high level. For the rare and lucky people who could afford it, it was really wonderful.

I understand that your obsession with James manifested itself beyond the runways?

I've searched through the Chelsea Hotel trying to find pieces in there, because you know he lived there and there are lots of myths about hidden dresses under floorboards. I hope they're not there anymore, I hope they got moved, but I've had multiple people tell me at different times in my life that they've seen them.

OK, last but not least, who's your date?

I'm dressing Dita Von Teese. I'm bringing her as an ode to James' work with Gypsy Rose Lee. You think of him as a designer to grande dames, but he was an American designer and America has that self-created ethos, and Dita certainly is a self-creation.

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