NEW YORK – The fashion industry spends a lot of time rhapsodizing about boy wonders, enfants terribles and hot young designers. There is something dazzling about a prodigy and watching a precocious new talent overturn assumptions can be energizing. But fashion also reveres youth because often, success in this industry – both commercial and critical — can be so short-lived.

After a dazzling debut, a brand is built slowly and arduously — one product category, red carpet victory, and industry award at a time. There are business hurdles to overcome – near catastrophes related to production or deliveries to stores. There may even be a bankruptcy. But those brands that persevere through those early years eventually emerge wiser, stronger and ready to tackle the really hard part: longevity.

There is a lot of ink spilled on the difficulties facing young designers and they, indeed, have a tough row to hoe. But in those early years, there is less to lose and everything to gain by taking risks – by putting everything on the line.

But once a brand has established an identity with shoppers, it has to evolve enough to remain consistently relevant, but not so much that its signature aesthetic becomes a blur. Oh, how our popular culture would be thrown topsy-turvy if Ralph Lauren suddenly began churning out conceptual, deconstructed caftans without armholes or if Calvin Klein suddenly started producing polka dotted tutus.

Designers must figure out how to attract new customers without alienating the old. And they must find a way to remain fresh, excited and curious even if they have reached the point of exhaustion.

Evolution is tough. But Charles Darwin was right; it is unavoidable. Sometimes the result is a more beautiful collection than ever before. But for spring 2015, evolution was often a little ugly.

But make no mistake; there was nothing unattractive on Michael Kors’ runway Wednesday morning. With sunlight pouring in the windows at Tribeca’s Spring Studios, models pranced down his runway looking utterly happy to be there – a fact that’s worth mentioning because it’s so rarely the case on any runway. Kors’ full skirts moved gracefully as the models walked and wide chocolate brown leather belts with leather corsages emphasized their waist. His knits were so fine as to be nearly translucent. Floral prints – daffodils and dahlias – brightened the simple cut of cropped tops and jackets. And he favored flat sandals with wide leather straps or pointy slingbacks with barely a one-inch heel.

Comfort was the focus, but luxury and optimism (Life is a lawn party!) – the essence of the Kors brand – were wholly evident.

Narciso Rodriguez stayed true to his architectural style, in which the elements of construction are part of the design, but his use of color departed from the expected in a delightful and surprising way. He mixed pink, clay and burgundy in a single dress. Pine green met dark mushroom in a tank. The collection bore his signature but without the familiar austerity. The spring collections have, in general, been an explosion of optimistic color. Rodriguez joined that conversation but without losing his distinctive vocabulary.

And designer Victoria Beckham also made a beautiful transformation, moving from a focus on tight-fitting sheaths to a more inclusive point-of-view that speaks to the many facets of the contemporary, urban woman. Beckham showed rough-hewn linen coats that stood away from the body, relaxed skirts and flat shoes. The tailoring was as sharp as always but with a bit more ease. She even smiled a little when she took her bow.

The greatest fashion feat, however, may be in reaching the designation of eminence grise. To be revered for past accomplishments, admired for current tastes and looked at with anticipation for what is to be. Few have arrived there. And yet, that is what Oscar de la Renta has managed to become with grace and conviction and the illusion of effortlessness.

De la Renta presents his collection in his own headquarters and on his own time – which is to say, on time. A habit that will be attributed to a perfect balance of impatience and confidence. Let’s get on with it! I’m ready!

His models emerged from a doorway covered in lush flowers – pink hydrangeas and carnations, if botany class serves. The runway was narrow so that the audience was pressed up close to the clothes for a proper inspection. De la Renta began with his more informal pieces, such as pale blue buffalo check shorts with matching kimono-sleeved tops, lace trimmed baby blue short with a delicate lace top, a black and white cotton canvas dress with a tulip print. There were dainty flat sandals with gold leaves stretching across the instep and flat oxfords with metallic details.

The more formal portion of his show wasn’t really formal at all. His floor-length gowns might have been cut in a grand silhouette, but they were stitched from lighthearted eyelet, embroidered with cheerful flowers or simply in a shade of tangerine that could only make one smile.

De la Renta’s skill – nurtured in the 1950s and ‘60s — is in combining technique with a light touch. His craftsmanship, so precise and rigorous, would be a bore if it were applied to dour shades of beige or gray, it would be pretentious without the charm of daisies adorning the bodice of a ballgown and it would be rather old-fashioned if everything was buttoned up and prim.

Designers many years de la Renta’s junior struggle mightily to remain relevant, to create collections that evoke pleasure in dressing up or at least stir up an intellectual curiosity in the exercise.

Donna Karan, who recently celebrated her company’s 30th anniversary, is also a fashion icon. “Donna.” That’s all anyone has to say in the context of style and those with even a passing familiarity with the industry knows that it’s a reference to Karan.

Along the way to this exclusive club, she has stumbled. In recent seasons, she has struggled to find a balance between her original seven-easy pieces – a formula for dressing intended to wardrobe women for conquering the world — and the air of sensuality that has always run through her work. Sometimes the art of seduction has led to collections that appeared more like Victoria’s Secret than sportswear. At others, the collection has been dull, like a fashion clinic on how-to-drape-jersey.

This season, she was inspired by Haiti, Africa, India – half the globe, it seems – and New York City. Mostly this meant that there were intriguing naïf patterns on her runway – black with strokes of bold color against tan. Stretch tops that gave the impression of being twisted almost haphazardly around the shoulders were often paired with the full skirts. Slender skirts with tribal prints were also beaded to emphasize the shapes. Sandals had high carved wooden heels. And Alice in Wonderland hats called to mind the tradition of carrying one’s belongings and wares atop the head. The sculptural hats rose up like water jugs or baskets.

Karan merged a host of disparate elements. Often the result was like a beautifully diverse tapestry. But sometimes, evening gowns bunched up around the hips or too much fabric made even the gazelle-like models look bottom heavy. Still, this was a collection in which passion and curiosity were palpable. There is no advancement in playing it safe. And Karan moves resolutely forward.

Unlike Karan and de la Renta, there are plenty of designers whose brands go on to become dull standbys. For them, the point of a fashion show is no longer to unveil some wonderful little delight that will thrill the eye and maybe shift the trends this way or that. They have ceased to engage in the rollicking fashion conversation. Instead, they dutifully churn out commodity t-shirts or handbags and shoes. They collect a regular check from licensees that have nothing to do with what they send down the runway.

The average Middle American shopper is unlikely to see much of what came down Tommy Hilfiger’s runway earlier this week in their local Macy’s. But that is probably for the better. Hilfiger spent a small fortune transforming the Seventh Regiment Armory on Park Avenue into the setting of a giant outdoor rock concert with a band shelter, grass, flowers, strings of light and invitations made from an old 45 rpm record. There was even a Hilfiger newsletter reporting on it all, which led one to wonder, why he even needed an audience.

The clothes were all familiar: striped blazers and skinny pants, patchwork jeans, filmy hippie dresses and metallic gold Chelsea boots covered in red and blue stars.

These were Woodstock costumes for a Coachella generation.

But at least Hilfiger’s collection had a certain good humor. Vera Wang, who began her design career creating elegant wedding gowns, was inspired for spring by bridal wear, Bohemia and “boyish boudoir.” That sounds lovely and spring like. But what came down her runway was black, wool and dour. The models were so pale they looked like they’d just endured a bloodletting. The clothes were heavy and, worse, familiar. The layers of short ruffles with raw edges, the short jackets with pleated peplums and the dark floral dresses shrouded in black netting were all familiar tropes in Wang’s brand. But they were not reworked in a surprising new way. They had not evolved. But worst of all, they just looked sad, worn out and old.