In 1947, the photographer Irving Penn made a black-and-white portrait of a young American musician. He is seated on drab carpeting draped over a chaise-like shape, vaguely old-world. The carpet’s mossy folds throw luxuriant shadows, and the musician upon them wears white tie and tails, a black overcoat caping his shoulders. He is relaxed, his left elbow propped on his left leg, which is hitched up on the seat, and his left cheekbone resting in his left hand as he gazes into the camera. His only visible ear, the right, is large—and as centrally positioned in the portrait as middle C. Is this a fin de siècle poet dressed for the theater? Is that a cigarette butt lying on the floor? Leonard Bernstein never looked more beautiful.

The following year, Penn took a black-and-white photograph of another young American artist, only here the subject is wedged between two walls forming a tight V—a Penn visual trademark. This man, barefoot and wiry, wears a turtleneck and black tights cropped at the calf. His feet press against the walls, a stride that suggests the Colossus of Rhodes. Yet his torso twists in another direction, and his arms are held tightly behind his back, hidden as if handcuffed. His expression is wary. Does the Colossus mistrust the camera or himself? Leave it to Jerome Robbins to choreograph a dance of inner conflict that lasts the length of a shutter’s click.

At this time, most of Penn’s subjects were middle-aged and long-established, but not these two. “Lenny” and “Jerry” were newly minted princes of the city—New York City, the postwar capital of the arts. Both were artists in love with classicism, trained in European traditions yet bending them to their new-world will. And both, in defiance of immigrant fathers who scorned the arts as a losing proposition, had their first big successes at the age of 25.

Each man in his own right was astonishing. Until his death, in 1990, Leonard Bernstein would be the most important musician in America, period. His fourfold eminence as a conductor of the world’s greatest orchestras, a composer of music in myriad forms, a concert pianist, and a teacher on television and at Tanglewood added up to a matchless legacy of accessibility and eloquence, gravity and theatricality, intellectual precision and ecstatic transport. He was a telegenic musical mensch—magisterial. Jerome Robbins, who died in 1998, was less public, a watcher whose uncompromising vision as a choreographer and director—in ballet and on Broadway, in shows filmed and on television—placed the power of dance before America’s baby-boomers and their parents. A storyteller in movement, Robbins daily murdered his darlings and those of his colleagues—dance phrases that were too fancy or distracting, music, text, and emotion that were too much. Truth, moment to moment, was all that mattered. He wasn’t a mensch. He was a perfectionist whose gypsy instinct for the essential, his eye as sharp as a shiv, demanded the best in others or just go home. Few chose to go home. And certainly never Lenny.

Both these men were about energy—positive, negative, generative—and while they racked up stunning achievements separately, they were elevated when joined. Put them together in collaboration—in masterpieces such as the joyous ballet Fancy Free, the breakaway musical On the Town, and the electrifying experiment West Side Story—and you had an ongoing theatrical Manhattan Project, work kinetically detonated, irreducibly true, and oh so American.

They were born within two months of each other, one hundred years ago, in 1918—Louis Bernstein, called “Leonard” by his parents, on August 25 in Lawrence, Massachusetts, and Jerome Wilson Rabinowitz on October 11 in New York City. When they first met, 25 years later, it was the kismet of kindred spirits, their upbringings variations on a theme: middle-class, Russian-Jewish, tough love from difficult fathers who were busy achieving the American Dream. Sam Bernstein did well in his own beauty-supply business, having grabbed the New England franchise for the Frederics permanent-wave machine, a device used in beauty salons, and Harry Rabinowitz, after moving the family to Weehawken, New Jersey, ran the Comfort Corset Company. While both men loved music, including the songs of the synagogue, and took pride in the accomplishments of their children (Lenny had younger siblings Shirley and Burton; Jerry an older sister, Sonia), they expected their sons to come into the family business and were horrified by the artistic ambitions blossoming in their homes. When a piano belonging to Aunt Clara was parked in the Bernstein hallway, Lenny, aged 10, found his reason to be. “I remember touching it,” he said, “and that was it. That was my contract with life, with God. . . . I suddenly felt at the center of a universe I could control.” For Jerry, who’d been playing violin and piano from the age of three and who began taking dance classes in high school, “art seemed like a tunnel to me. At the end of that tunnel I could see light where the world opened up, waiting for me.”

Note the shared language of rapture. “Jerry just breathed theater,” says the composer and lyricist Stephen Sondheim, who worked with both men. “Lenny had a really wonderful sense of theater, but he breathed music.”

Still, there were crucial differences. Lenny’s mother, Jennie, doted and adored, while Jerry’s mother, Lena, was impossible to please (a favorite gambit: if Jerry misbehaved, she would pretend to call the orphanage with a donation—him). Lenny was educated at Harvard and then on scholarship at the Curtis Institute of Music. Jerry, who had to leave New York University after one year because it was too expensive, was permanently insecure about his lack of education. And when it came to being Jewish, Lenny was proud of his heritage. He cherished memories, dating back to his boyhood, of the times he and his father sang together at temple. When Serge Koussevitzky, one of the several conductors who mentored Lenny, and himself a Jew, suggested he Anglicize his name to Leonard S. Burns, he replied, “I’ll do it as Bernstein or not at all.” (Pronounced Bern-stine, with a long i.)

For Jerry, being Jewish brought shame and fear. Asked to say his name on the first day of first grade, he began to cry. “Rabinowitz” was so not American. “I never wanted to be a Jew,” he would write in notes for an autobiography. “I wanted to be safe, protected, assimilated.” Once he began performing, his name changed program to program, from Robin Gerald to Gerald Robins to Jerry Robyns to Gerald Robin to Jerome Robbins. It is often said that Leonard Bernstein wanted everyone in the world to love him; while still in college he said as much to a close friend. Lenny lived with arms open. Jerry did not feel lovable and was deeply guarded. At the height of his mastery on Broadway he insisted that his billing include a box around his name, showcasing his contribution, protecting it, arms crossed around it.

They met in October of 1943, the beginning of what Bernstein would call “the year of miracles.” Bernstein was living in New York City, marking time as the assistant conductor of the New York Philharmonic, and Robbins was in the classical company Ballet Theatre. Both were hungry for the Big Break, but it was hard to see anything on the horizon. Bernstein’s would come a month later, when on November 14 he took the podium at Carnegie Hall—without rehearsal!—and conducted for the ailing Bruno Walter. This kiss of fate allowed him, in one afternoon, to loosen forever Europe’s grip on the conductor’s baton. His debut made the front page of The New York Times, and the skinny kid, soon dubbed the Sinatra of the concert hall, soared to stardom. Two months later his Symphony No. 1, Jeremiah, was premiered.

Robbins had to make his own luck. Though a dazzling mimic and scene-stealer in character roles, he was tired of dancing courtiers and exotics in the corps. He wanted to choreograph ballets that were immediately American. After inundating company management with over-ambitious ideas for ballets, Robbins finally offered up a timely, simple scenario—three wartime sailors on shore leave in Manhattan. Management bit. All he needed was a score, which took him to Bernstein’s studio in Carnegie Hall.

On that October day in ‘43, Robbins described his ballet—not yet titled Fancy Free—and in answer Lenny hummed the tune he’d written on a napkin that afternoon at the Russian Tea Room. Jerry flipped. The sound was spontaneous and streetwise. “We went crazy,” Lenny recalled. “I began developing the theme right there in his presence.”

“The one thing about Lenny’s music which was so tremendously important,” Robbins said later, “was that there always was a kinetic motor—there was a power in the rhythms of his work, or the change of rhythms in his work and the orchestration—which had a need for it to be demonstrated by dance.”

‘I remember all my collaborations with Jerry in terms of one tactile bodily feeling,” Bernstein said in 1985, “which is his hands on my shoulders, composing with his hands on my shoulders. This may be metaphorical but it’s the way I remember it. I can feel him standing behind me saying, yes, now just about four more beats there . . . yes, that’s it.”

This was the kind of hands-on collaboration that Bernstein—who never liked being alone in a room—would always love. And it wasn’t metaphorical. Carol Lawrence, the original Maria in West Side Story, has said that “Lenny would bring in new music and he would play it for us. And Jerry would be standing over him and he’d clutch Lenny’s shoulders as if he were a musical instrument. He was always capable of coming up with a new melody, whatever Jerry needed.”

Key words: “standing over him.” In their relationship, Jerry was the leader, dominant, the overlord—everyone says this—and Lenny was flexible, with quick response time and an inexhaustible archive of musical forms from which to pull. Bernstein was steeped in the classical repertory, and he was a savant when it came to rhythm. “We were always embarrassed by his dancing,” says his older daughter, Jamie Bernstein. “But when it was put into the context of conducting or composing, suddenly his sense of rhythm was spectacular—it’s what gives his music a thumbprint. There’s no explaining why he had this incredible aptitude for rhythm, but it is true that he synthesized what he got out of Hebrew cantillation, and the music and dancing in that world, combined with his getting really obsessed with what were called race records, in his college years—Billie Holiday and Lead Belly—to say nothing of Stravinsky and Gershwin. Add the Latin-American thread, which came in around 1941, when he was in Key West, and he just went bananas.”

Because Robbins was touring with Ballet Theatre, much of the collaboration on Fancy Free’s score took place through the mail. Exuberance shoots through Lenny’s updates, letters of magical rapport and full of cocky confidence, just like the sailors in the ballet. A letter of late 1943: “I have written a musical double-take when the sailor sees Girl #2—has that ever been done before? And the rhythm of your pas de deux is something startling—hard at first, but oh so danceable with the pelvis!” Some friends who knew them then have said that Bernstein and Robbins had a brief affair. Others say not. But this was one more thing that Lenny and Jerry had in common—bisexuality. At the very least, the letters are full of excitement.

And the excitement was realized. Fancy Free was one of the greatest hits in ballet history—22 curtain calls on opening night, April 18, 1944. With a set by Oliver Smith, evoking the city at dusk, the ballet was a perfect little playlet, a New Yorker short story out of Jerome Robbins, so clearly articulated in movement slang and classical momentum that words would have been overkill. Lenny conducted, and his buoyant presence, that too was choreographic. “His downbeat, delivered against an upward thrust in the torso, has an instantaneous rebound, like that of a tennis ball,” wrote the distinguished dance critic Edwin Denby. “And you could see that the dancers, even when they came on tired, responded to Mr. Bernstein like hepcats to Harry James.” Bernstein’s physical brio on the podium would become a signature—the “Lenny dance,” he called it.

“We’re 70 years on in the life of that ballet and it is so alive,” says Damian Woetzel, the incoming president of the Juilliard School and a former principal dancer at the New York City Ballet, where he danced Robbins’s own role in Fancy Free. “These were true American voices that were addressing what it meant to be American, through dance and music. And finding their foothold at a moment when America, during the war and afterwards, is becoming more and more indispensable—as a country and as a force. I see Fancy Free as their mighty yawp. There they are—wham—they’ve arrived.”

Shortly after Fancy Free’s premiere, Robbins was already pushing the envelope, thinking about a “ballet dance play in one scene, combining the forms of dance, music, & spoken word into one theater form.” It didn’t come to anything at Ballet Theatre, but when Oliver Smith suggested that the situation of Fancy Free might be retooled into a Broadway show, spontaneity and content merged and the result was On the Town. That a whole show could bounce out of a short ballet attests not only to the emotional richness of Fancy Free but to the ready invention of Robbins and Bernstein, now joined by the madcap writing team Betty Comden and Adolph Green. As Adam Green, Adolph’s son, wrote in these pages, the four agreed that “all the elements of the show would work as an integrated unit, with story, songs, and dancing all growing out of one another.”

It was musical theater cracked open, the plot morphologically cascading, evolving itself scene to scene. Bernstein revealed a gift for lyric simplicity, and his shake-a-leg symphonism, which shot between highbrow dissonance and brash Big Band, had the glitter of mica in Big Apple sidewalks. “The harmonies, the way that Bernstein wrote the city,” says Paul Gemignani, musical director of Jerome Robbins’ Broadway, in 1989, “it sounded like New York in 1944, as opposed to New York in Gershwin’s time.” Bernstein was blown away by Robbins’s acute theatrical instincts—”incredible, musically.” Yes, Jerry’s instincts were already impressive.

A mere eight months later, on December 28, 1944, On the Town opened on Broadway, directed by that granddaddy of the stage George Abbott. It was a show, the critic Louis Biancolli wrote, “planned, worked out, and delivered in a ballet key.”

“It was audacious,” says the director Harold Prince, who while still in college saw the musical nine times. “I thought, I’ve never seen classical music, classical ballet, and a lighthearted zany show all put together and make sense. I loved it so much, and at the same time, more subconsciously, I was trying to see how those disparate elements came together to make such an incredibly successful evening.”

‘When I talk of opera,” George Abbott wrote to Bernstein a year later, in 1945, “I am talking about a new form which does not now exist: I am talking about something which I expect you to create . . . unhampered by tradition.” Paging West Side Story. The subject for this “new form,” however, came not to Bernstein but to Robbins, in 1947. Helping his lover, the actor Montgomery Clift, figure out how the role of Romeo might be refashioned in the present tense, Robbins thought, Why not create a contemporary Romeo and Juliet? In 1949, a first try by Robbins, Bernstein, and the writer Arthur Laurents, which substituted Catholics and Jews for Capulets and Montagues, went nowhere. But in 1955, with gang violence making headlines, Laurents suggested a shift to rival street gangs. Robbins insisted that the show be cast with young unknowns who could dance as well as sing—because dance is a tribal language, primal and powerful. The fusion of forms would be as snug as a switchblade, and the musical would move as the crow flies, direct and dark. The New York premiere was September 26, 1957: Jets and Sharks; Polish-Irish-Italian Americans vs. Puerto Ricans; Tony and Maria. Robbins was the engine and Bernstein the environment, his score sui generis—a rite of spring inside a Ben Shahn line drawing.

The genesis, impact, and influence of West Side Story has been explained and analyzed in countless histories and memoirs. Its team—Robbins, Bernstein, book by Arthur Laurents, lyrics by the fledgling Stephen Sondheim—is perhaps the most brilliant in Broadway history. Hard to believe now that the suits at Columbia Records, when Bernstein and Sondheim auditioned the score for them, thought it was too advanced, too wordy, too rangy—and no one can sing “Maria.” This masterpiece continues to defy category, though Laurents came closest when he called it “lyric theater.” As Martin Charnin, an original Jet who went on to direct and write his own shows, says today, “You know how there’s Mount Everest and then there are mountains? As far as I’m concerned, there’s West Side Story and then there are musicals.” This was the pinnacle of the Bernstein-Robbins enterprise.

‘I will never, never work with Jerome Robbins again, as long as I live”—long pause of silence—“for a while.” Gerald Freedman, Robbins’s assistant director on West Side Story, remembers Bernstein saying this over dinner, after the show opened. By 1957, the differences between Bernstein and Robbins, which Irving Penn captured so well in those portraits of ‘47 and ‘48, were far more pronounced. Bernstein had married the sublime Felicia Montealegre Cohn, a Costa Rican–born actress and musician, in 1951; he was now the father of Jamie and Alexander (Nina yet to come); and he had just signed on as music director of the New York Philharmonic. It was a celebrated, expansive, and overstuffed life, extremely social, his time for composing dovetailed in with difficulty. Robbins, meanwhile, was indeed a colossus with a Broadway hit parade to his name, shows including High Button Shoes, The King and I, Pajama Game, Peter Pan, and Bells Are Ringing. (Gypsy was just around the corner.) But he was still uncomfortable in his own skin, hot-tempered with his collaborators, and a slave driver at work, demanding every minute, every second, of time owed him. It didn’t help that in 1953, threatened by the House Un-American Activities Committee with a public outing of his homosexual relationships, Robbins named names. Felicia Bernstein didn’t speak to him after that, or not much, and wouldn’t have him in the apartment. When he went over to work with Lenny he headed directly to the studio. In fact, there were only two people that Lenny deferred to: Felicia and Jerry. Both could make him sweat. Regarding Jerry, Bernstein’s view was simple: We have to cater to genius.

“A genius for me means endlessly inventive,” says Sondheim. “With the accent on the ‘endlessly.’ Jerry had this endless fount of ideas. And, man, you couldn’t wait to go home and write after you got finished talking to Jerry. Nobody matches Jerry in musical theater. Nobody had Jerry’s invention. Nobody.”

The problem was that “Jerry worked best when it was all instinct,” says the playwright John Guare. “And the one thing that Jerry did not trust was his instinct.” His infernal second-guessing—an aesthetic integrity that had him tossing out thrilling ideas in search of even better, truer ones—could get maddening, irrational. “Dostoyevsky territory,” Guare calls it. And despite his wit and charm after hours, Robbins at work used confrontation and cruelty to get his way. “Black Jerome” was Bernstein’s nickname. During the dress rehearsal of West Side Story, right under Lenny’s nose, Black Jerome simplified the orchestrations of “Somewhere” without batting an eye.

“Our father was fearless,” says Alexander Bernstein. “But when Jerry was coming over and there was a big meeting, he was scared.” In the company of geniuses, Jerry was primus inter pares, first among equals.

“No matter what the material was,” says Guare, “if Jerry wanted to do it, people would follow him.” And if the material wasn’t right? In 1963, Robbins asked Bernstein to help him make a musical of Thornton Wilder’s apocalyptic The Skin of Our Teeth. They started, but, as often happened, other obligations got in the way—for Lenny, the Philharmonic; for Jerry, Fiddler on the Roof. In 1964 they returned to the Wilder with high hopes; Comden and Green were now on board and New York was waiting. Six months later the project was abandoned, no explanations. Privately, Bernstein called it a “dreadful experience.” The Robbins biographer Amanda Vaill suggests that Robbins may have become just too authoritarian for his On the Town family. Robbins himself wrote, “We did not want to think of a world after a nuclear war.” Adam Green’s understanding from his father was that “Jerry got restless and walked away, and then Lenny did, too.”

Worse was Robbins’s attempt in 1968, revisited in 1986, to turn Brecht’s play The Exception and the Rule into a sort of musical vaudeville, a torturous episode for everyone involved, especially Bernstein. “The material refused to be transformed,” says Guare, who was brought in to write the book. “It was like dealing with a dead whale in the room. Lenny kept saying to Jerry, ‘Why do you need me in this show?’ He was afraid he was just being used to supply incidental music and he wanted to make a statement that would give it importance. Jerry would not give him that opening.” Again, Jerry walked out of the project—in the middle of casting, no less—and Lenny burst into tears.

“Yup,” says Paul Gemignani. “It’s not going to work. There’s no boss in the room.”

Bernstein’s “never, never—for a while” always passed. His letters are filled with his and Jerry’s ideas for collaboration, and Jerry’s journals reflect continuing awe at Lenny: “He hits the piano & an orchestra comes out.”

“A collaboration as frequent and close as theirs is a marriage,” says Sondheim. “As a collaborator I’ve had a lot of marriages. That’s exactly what’s involved.” Bernstein and Robbins admired and antagonized each other, exhilarated and wounded each other, loved and at times hated each other. They were both, Jerry wrote in his journal, oversensitive and insensitive: “he scared of me & me feeling he always put me down.” Yet neither one ever thought to let this artistic marriage go. At their best, they completed each other.

“The need for Lenny to work with Jerry,” says Charnin, “was just another side of the coin that was the need Jerry had to work with Lenny.”

“They would both do other things,” says Jamie Bernstein, “but then they would try again together to achieve this higher thing that they were both so obsessed with. They loved to break down the walls between genres, making things more fluid.”

“Obviously, if you break boundaries,” says Harold Prince, the producer of West Side Story, “you want to break further and larger boundaries. Jerry wanted to dig deeper and deeper. And Lenny could deliver. He had a sense of size—no borders, no boundaries.”

“They were two extraordinary balls of energy,” says Guare, “two spinning dynamos occupying the same space. And they each needed success. They had in common a hatred of failure. When their strengths came into alignment it was like the stars aligning. But there was no control over that.”

Their last collaboration to see the stage was a work they had wanted to do since Fancy Free’s premiere. In 1944, flush with the future, they were both drawn backward to a Yiddish classic of 1920—S. Ansky’s play of love, death, and possession, The Dybbuk, or Between Two Worlds. The work was tailor-made for them. It spoke to their shared lineage as Russian Jews. It told the story of soulmates Chanon and Leah, and the mystical link between them. (“When you make your first work with someone,” Robbins would say in an interview before Dybbuk’s premiere, “it makes for a certain bond.”) And the play’s focus on the existential secrets of the Kabbalah had a Promethean subtext, the reaching after cosmic—read artistic—power. But it didn’t happen then. Success carried them away from Ansky and straight to On the Town. Two more Robbins-Bernstein ballets came in 1946 and 1950—Facsimile and Age of Anxiety, both psycho-analytically probing—but they are now lost.

“Dybbuk Dybbuk Dybbuk,” Robbins wrote to Bernstein in 1958. “With this ghost’s effort I know that suddenly something will be on paper that will get us all started.” They finally made a start in 1972, and, when N.Y.C.B. scheduled Dybbuk’s premiere for May 1974, expectations ran high. “It was a big, big deal, Lenny and Jerry working together again,” remembers Jean-Pierre Frohlich, who oversees the Robbins repertory at N.Y.C.B.

Robbins had come to a place of peace about being a Jew. A trip to Masada, in Israel, had moved him profoundly. According to Dan Duell, the artistic director of Ballet Chicago, Robbins “wanted to capture the rarefied atmosphere that was still alive and breathing there. Dybbuk was an attempt to evoke the magical spirit of their heritage.” Robbins planned to dramatize the story, to play to his greatest strength. Bernstein wrote a magnificent score—brooding, gliding, gleamingly nocturnal. But then Robbins backed away from narrative and into abstraction. “It was a very precious subject to Jerry,” says former N.Y.C.B. dancer Bart Cook, “one that he really wanted to do—but was afraid of. You should have seen some of the scenery, gold-covered flames, and the Kabbalah stuff and the symbolism. He just axed it all. It was too exposing.” When Bernstein told People magazine, “The ballet is based on our experience in Jewishness,” Robbins corrected him: “It isn’t.”

“I want to seize a clear and brilliant diamond,” says Chanon in Ansky’s play, “to dissolve it in tears and draw it into my soul!” Robbins was no doubt referring to this line when he said, some years later, that he’d wanted to make “a very hard diamond of a ballet.” Perhaps he couldn’t see it at the time, but that’s exactly what he and Bernstein made—a black diamond, glinting with astral refractions. Patricia McBride, the first Leah, loved dancing Dybbuk. “I felt totally immersed in it and lost,” she says, “lost in the music.” Dybbuk comes back into N.Y.C.B. repertory this spring, a tale of two souls fated and luminously fused. Until the end of their lives, Lenny and Jerry’s respect for each other, their mutual support, never wavered.

Perry Silvey, the longtime technical director of the New York City Ballet, remembers running a rehearsal sometime in the late 80s. It was a quiet ballet, and there was noise above the stage, coming from the galleries where the fly-floor guys and bridge-spot operators work. “As we were rehearsing we keep hearing guys talking,” says Silvey. “I’m out in the house and even the dancers are kind of annoyed. Over the headset I said, ‘Please, guys, keep it down. There’s too much talking going on.’ And this happens a couple of times. Finally I walk all the way up onstage and yell, ‘Quiet on the gallery!’ I look up and there’s Jerry and Lenny, side by side, looking over the rail at me. They were probably up in Jerry’s office—there’s a door from the fourth-floor hallway that goes right into that gallery—and they just sneaked in to look down and see what was happening onstage. They were having a real good time, obviously. And when the two of them, old pros, realize they’ve been in the wrong, the most hilarious thing—they both cover their mouths with their hands and almost giggle, and then slink away like two schoolboys.”

Or like two boy wonders—co-pilots on the same comet.