Louis Kahn died suddenly of a heart attack in Pennsylvania Station in New York 43 years ago, in circumstances that made it the most startling end to an eminent architect’s life since Stanford White was murdered by the husband of one of his lovers. Kahn ranked among the most revered architects in the world, but he had the appearance of a somewhat disheveled old man, and after he collapsed on the floor of the men’s room, his corpse remained at the city morgue for more than two days before anyone discovered that he was an internationally respected cultural figure and not a vagrant.

This bizarre state of affairs didn’t end with Kahn’s death. Eventually, the New York Police Department made contact with his wife, Esther, who arranged to have the body brought home to Philadelphia, where she presided over his funeral accompanied by the couple’s daughter, Sue Ann. But elsewhere in the chapel were two younger children that Kahn had sired by two different women—all while married to Esther. Recognizing that she could not make her husband’s other two families disappear, Esther sent word before the funeral that they were to be seated out of her line of sight.

The strange saga of Kahn’s private life was largely kept from the public eye. His front-page obituary in The New York Times mentioned only Esther and Sue Ann; the Times was not aware of Kahn’s other children, Alexandra Tyng and Nathaniel Kahn, and given the paper’s views on such matters in 1974, the editors would almost certainly have forbidden any mention of them if they had known. The family’s story wouldn’t gain wide currency until 2003, when Nathaniel, now a successful filmmaker, released My Architect, a highly acclaimed film about his quest to know his father.

Today, Kahn is revered among architects and architectural historians as one of the greatest—perhaps the greatest—American architect since Frank Lloyd Wright. His oeuvre is small by Wright’s standards, but it contains an astonishing number of masterpieces: the First Unitarian Church in Rochester, New York (1962); the Salk Institute in La Jolla, California (1963); the library at Phillips Exeter Academy (1971); the Kimbell Art Museum in Fort Worth (1972); the Indian Institute of Management in Ahmedabad, India (1974); the Yale Center for British Art in New Haven (1977), finished after his death; the capitol buildings in Dhaka, Bangladesh (1983); and then a remarkable posthumous work, the Four Freedoms Park, a memorial to Franklin Delano Roosevelt in New York City, which Kahn designed shortly before his death and which lay dormant for years until it was finally completed, to wide acclaim, in 2012.

None of these are particularly easy works to experience. They are not visually spectacular in the manner of Frank Gehry, and they do not dazzle with their sleekness in the manner of Renzo Piano or Norman Foster. Kahn’s architecture does not cuddle you. It is not soft, and it is not whimsical. He designed somber, poetic buildings of stone and steel and wood and glass, and the best of them are brooding and deep, like a Rothko painting. The interior of the Unitarian church in Rochester is made of concrete blocks, and it would feel harsh but for the perfection of its proportions and the sublime way in which the light washes down into the worship space.

Kahn led a generation of architects away from the standard-issue modernism of glass and steel boxes, but his route was gentle, thoughtful, philosophical, and sometimes vaguely mystical, which is part of the reason that he never really became famous. Kahn’s semi-obscurity didn’t just extend to the cops at Penn Station: The Times obituary had to be written on deadline the night his death became known, because the obit editors hadn’t considered him important enough to merit one in advance. (I am quite familiar with the circumstances, because I was the young staff critic who was pulled into the office that night to write it.)

As Wendy Lesser’s ambitious new biography, You Say to Brick, makes clear, Kahn’s impact on architecture was vastly out of proportion to his fame—and that, more than anything, marks him as a figure out of the past. Fame, after all, is the coin of the realm in architecture these days, and architects like Gehry, Rem Koolhaas, Bjarke Ingels, and the late Zaha Hadid are household names in a way that Kahn never was.

Kahn’s career developed slowly; even his own profession didn’t pay him serious heed until he finished the Yale Art Gallery in 1953. At the time, he was already 52. His career was a series of deliberate, unhurried efforts; he worked over his designs with such obsessiveness that he lost money on many of his jobs and died in debt. Contrast him with Ingels, one of today’s leading architects: Kahn spent most of his late 30s “in fits and starts of professional activity,” Lesser tells us, noting that “much of it was unpaid” as he struggled to find his way as well as clients who understood his sensibility. Ingels, on the other hand, is barely past 40—he was born the same year Kahn died—and seems to announce a new project on a different continent every week. (He also has over 285,000 followers on Instagram and around 81,000 on Twitter.) The gleeful merger of architecture and celebrity expressed by the word “starchitect” is the antithesis of everything that Kahn embodied.

In some ways, Lesser’s subject in You Say to Brick isn’t only Kahn, but also the shift in culture that has made this philosopher-cum-artist-cum-architect seem so out of sync with the times. Lesser doesn’t rail against this cultural shift; she’s too smart a writer to waste her time tilting against the windmill of celebrity architecture. Instead, she plays with the form of architectural biography to create a narrative that at once seems to accept the realities of our time and to transcend them.

Lesser knows that the story of Kahn’s death is compelling, and unlike the architect’s previous biographer, Carter Wiseman (whose solid, workmanlike Louis I. Kahn: Beyond Time and Style reduces his death to a paragraph toward the end), Lesser opens her book with a 19-page account of the story, detailing every one of Kahn’s steps—he was traveling back to Philadelphia from India—as well as every painful phone call that both his distraught wife and his secretary made as they searched for him.

Lesser has a flair for drama, and unlike Wiseman—who seemed to fear that devoting too many pages to Kahn’s difficult personal life might undermine the reader’s view of him as an architectural master—she gives us a more complex portrait of a man who lived with great intensity, if not angst, and whose determination to follow his own path played out in his emotional life as fully as on his drawing board. This is not to say that Lesser’s book is sensationalist; when all is said and done, she manages to confer as much dignity on the architect as Wiseman does.

Where Lesser does get carried away, paradoxically, is when she tries to make it clear that this is a book about architecture with a capital A. In the prologue, for example, she paints Kahn’s character in broad yet sensitive strokes, introducing us to his gnomic rhetoric (“You say to brick, ‘What do you want, brick?’ Brick says to you, ‘I like an arch.’”), his background and family, his ambivalent relationship to his Jewishness, and his deep emotional relationship to architecture. Then she goes into a long disquisition on the differences between the monumental 30th Street Station in Philadelphia and the glorified subway station that replaced New York’s original Penn Station. This set piece is intended to illuminate the power of great architecture, and it also sets the stage for Kahn’s death in the very first chapter. But while Lesser evokes the timeless grandeur of the 30th Street Station beautifully, the connection is more than a bit contrived, and it is curious that the first building discussed in detail in this book is one that Kahn didn’t design.

Biographies of architects—or, indeed, of any creative figure—are rarely the best way to learn about an artist’s actual work. The narrative arc of the life and the critical discussion of the art never fit seamlessly together, and even the greatest, most knowing biographies, like Mark Stevens and Annalyn Swan’s de Kooning, require some familiarity with the artist’s work or, failing that, a monograph or book of art history by one’s side.

Lesser, with admirable ambition, tries to develop an alternative model for architectural biography: Instead of giving us Kahn’s life story as pure narrative, she interweaves five chapters that she calls “In Situ,” essays on several of Kahn’s buildings: the Salk Institute, the Kimbell Museum, the Phillips Exeter Library, the National Assembly of Bangladesh, and the Indian Institute of Management. These are not so much critical essays as guided tours, telling us how Lesser has experienced these buildings and conveying some of her emotional connection with them.

Lesser is an engaging guide, and these essays work wonderfully at breaking up what can be, even in the finest biographies, the tedium of recounting a life as it played out year by year. But I’m not entirely sure the experiment works. The “In Situ” chapters rarely fall at the point in the narrative when Kahn is actually designing the buildings, and they can therefore be confusing for the reader. They also risk exaggerating the importance of these five buildings at the expense of others.

Maybe neither of these things matter. Lesser has, after all, accomplished something very important here: She has made us conscious that her book is about an architect, and not about an unusual, eccentric, brilliant, warm, determined, difficult, kind, and arrogant man who happened to design buildings for a living. She has also helped us feel the powerful emotional connection to space and form and light and materials that Kahn himself felt, and that is far more than most architects’ biographies manage to do.

But I found myself wondering whether these “In Situ” essays, intelligent, knowing, well researched, and gracefully written as they are, served another purpose as well: They seem to function as an implicit acknowledgment that, however hard she tries, no biographer can get completely inside her subject’s creative process. You can dive deep, but you won’t touch bottom, because genius, or the way in which genius expresses itself in creative work that other people can appreciate, isn’t really open to explanation.

Lesser can tell us a great deal about Kahn— where he came from, how he lived, what he aspired to—and she can tell us a great deal about the extraordinary buildings that resulted from his passion and brilliance. But exactly what went on in his head at the moment his pencil touched the yellow tracing paper on which he made his exquisite, telling sketches isn’t something that Kahn himself may have been able to articulate, and it certainly isn’t something that any biographer can fully convey.

It is to Lesser’s credit that while she tells us plenty about Kahn’s struggles to get his unusual buildings constructed in a world that favors the mundane, the quick, and the cheap, the heart of her story, the struggle that matters most to her, is the one that Kahn had with himself, as he tried to figure out how to solve architectural problems in a way that would make his buildings emotionally resonant to those around him.

Kahn liked to talk about how all of his creative efforts began at “Volume Zero,” as if to say that every time he took on a new project, he tried to peel back everything he’d known or done to that point and figure out some basic, primal way toward a solution. He studied history carefully and, as scholars starting with Vincent Scully have shown, was influenced by the great architecture of the past. But for Kahn, it was always a matter of absorbing the feeling more than copying the form of an earlier work, and he consistently sought new ways to achieve the aura of monumentality that he so desired.

A determined modernist, Kahn leaned left politically, but his aesthetics (or at least his profound commitment to aesthetics) could often be at odds with his political stance. The left has had a somewhat ambivalent relationship with the veneration of monumental space and form that so captivated Kahn: It can seem extravagant, an act of indulgence that distracts from the urgent business of getting people housed, clothed, and fed. But to Kahn, choosing between social responsibility and aesthetics was never a zero-sum game. His worldview was based on the belief that great architecture, like great art, was an experience that everyone had the right to have. Another architect could put roofs over people’s heads; Kahn wanted to give them temples.

Partly because few commercial clients had the patience to work with him, Kahn built mainly institutional and public buildings, along with a handful of residences, though none of these rank among his finest work. He preferred to design museums, religious structures, and civic buildings because these kinds of structures also gave him the opportunity to think hard about how architecture could influence public life. He did not think of his buildings as pure works of art, as places in which to escape the mundane. Rather, he thought that the aesthetic experience of architecture could elevate everyone and that this, in turn, might raise the level of civic life. He believed that if the aesthetics were of the highest order, something approximating a sense of belonging and responsibility might follow.

The earnestness of this belief dates him as much as his relative lack of public renown. Kahn cut his teeth in the age of the New Deal, and to a great extent he never lost his belief in the idealization of the workingman that was central to its programs. But it wasn’t only those formative years that gave him this faith: Kahn may have also been the least cynical architect of modern times. He wasn’t lacking in ambition or ego, but his drive expressed itself as an almost religious belief in the potential of architecture to make life better.

You get his essence almost as much through his words as his buildings. Both are somewhat spare and cryptic, and both are rich in meaning. Who else but Kahn could have said, “A great building must begin with the unmeasurable, must go through measurable means when it is being designed and in the end be unmeasurable…. what is unmeasurable is the psychic spirit.” Or, “The sun never knew how great it was until it struck the side of a building.” Or, “I want to give the wall a consciousness.”

Kahn’s writing could dance on the edge of psychobabble, and we almost certainly would have been less forgiving if his architecture hadn’t been as good as it was. But at their most evocative, Kahn’s words don’t give us insight into his buildings so much as they do him and the reasons behind his designs. Kahn spent his life in pursuit of the distinct feeling of awe that he believed architecture could instill in others. His rambling, poetic pronouncements were his way of trying to get at the essence of what he sought in architecture: not just to protect us from the rain, but to provide us with a kind of spiritual shelter.

“Did the world need the Fifth Symphony before it was written? Did Beethoven need it? He designed it, he wrote it, and the world needed it. Desire is the creation of a new need.” In these lines, delivered by Kahn at the International Design Conference in Aspen, we can see what he really wanted from his buildings. The day-to-day stuff was all well and good—“need is just so many bananas,” he liked to say—but the only thing that truly mattered to him, in the end, was that architecture had to aspire to something more than merely practical concerns. For Louis Kahn, the test of architecture was in its lasting emotional impact. Did we know we needed his buildings until we experienced them? Perhaps not. But after walking through his Kimbell Museum, or his Salk Institute, or his British art center, it is impossible to imagine a world without them.