In the city of Syracuse in Sicily, there is a building that has served as the spiritual center of the place for more than 2500 years. Now a church, it frowns down on the piazza from behind a weighty Baroque facade, but on its flanks, embedded in the unadorned side walls, one can still see the scarred columns of the Greek temple it once was. The spaces between them are blocked up with the masonry of centuries now, and the interior of the building; which in pre-Christian times opened up freely on the disorderly life of the city, has been made dark, private and inaccessible.

In a provocative and erudite new book, The Conscience of the Eye: The Design and Social Life of Cities, Richard Sennett argues that the past two millennia have seen the construction of walls of isolation and introspection around the human soul. In particular, he believes, the structure of the cities we inhabit has both prompted and reflected an increasing tendency to separate the spiritual and social aspects of our lives. The physical qualities of public spaces no longer express the complexities of our psychic existence; when we wish to contemplate, we withdraw. In places like classical Athens, Sennett writes:

"The temples, markets, playing fields, meeting places, walls, public statuary, and paintings of the ancient city represented the culture's values in religion, politics, and family life. It would be difficult to know where in particular to go in modern London or New York to experience, say, remorse."

Our cities, Sennett argues, obliterate value instead of creating it. Beguilingly democratic, they neutralize unequal and unpredictable landscapes with grid patterns that provide useful chessboards for economic competition. The standardizing grids expand not just outwards, but upwards, in skyscrapers whose sixth floors and 60th floors are identical, as well as across time, thanks to the modern invention of clocks to "cut time into meaningless fragments of deadening routine."

In such a setting, there is nowhere to go but about one's business. People become passers by, moving through neutral spaces between private point and private point, between home and office, insulating themselves from the unexpected. The Conscience of the Eye is an attempt to explore the origins and implications of this condition of insulation, to explain the curious feeling of unconnectedness that is familiar to anyone who has passed a homeless man on a grate, or observed through plate-glass windows the comings and goings of strange offices and apartments.

The title of Sennett's book belies the breadth and scope of its arguments. This is not just a work on architecture or urban history, although it makes extensive use of both. It is, rather, a breathless, engaging romp through the alleyways and avenues of Western civilization. The route it takes is determined not by chronology, not by geography, but by the enthusiasms of the author's intellectual imagination.

Sennett, who teaches sociology at New York University, is a true humanist from the Renaissance mold, and his impressive scholarship is hemmed in by none of the constricting categories in which most of his colleagues in modern academia confine themselves.

He ranges freely and effortlessly through history, literature and philosophy, taking the reader in the course of a few pages from the Harlem of James Baldwin to the Rome of Sixtus V, from Edmund Spenser to Hannah Arendt to Mies van der Rohe.

Much of the time, The Conscience of the Eye does not just invite rereading--it demands it. The book is difficult without ever being jargony or abstruse; like his ideas, Sennett's prose is densely packed and complicated. In his aesthetics as well as his social philosophy, he is heavily influenced by modernist and existentialist demands for involvedness and interaction. In fact, Sennett's language creates for the reader exactly the kind of environment that he hopes our cities will one day embody. It is a landscape of the unexpected, of twists and turns and delightful discoveries. Familiar monuments spring to life, like Pushkin's bronze horseman, to claim a place as actors in the drama of history.

Like many New Yorkers, Sennett sometimes fails to put the city in context. Non-urban areas are blank spaces on his world map, merely waiting to be filled in by the encroaching grid. The city is never presented as an alternative location among many. Sennett's arguments would have been strengthened, for example, had he considered the role of the wilderness as the accepted zone for today's spiritual quests. Surely the modern citydweller's solitary journey to the mountains or the ocean in search of meaning and fulfillment is in a fundamental way a pessimistic, escapist denial of the possibilities that human society offers.

The Conscience of the Eye is not a sentimentalist tract. It issues no call for a neoclassical revival, for an America dotted with cinderblock Romes and girdered Spartas like some overgrown theme park. Rather, this extraordinary book attempts to rebuild the Roman civitas and the Greek polis as much in our selves as in our surroundings. It proposes to break down walls and open up spaces to reveal vistas too long blocked off from view. And even if this book causes no cities to be razed or rebuilt, it will surely broaden avenues in its readers' minds