Peter Gay has written a sweeping survey of Modernism that is lucid, highly readable, amply illustrated, beautifully designed, and remarkably complete. He has, essentially, written a survey of 120 years of cultural and aesthetic history. This is not a task for the faint of heart, but Gay has never suffered from that malady, his array of works spanning multiple centuries. His two-volume history of the Enlightenment remains a very important study and his work on Freud and on 19thc sensibility equally so.
The problem with Modernism is that there is so much of it, particularly if you set out to write about poetry and fiction, music, architecture, painting, pop culture, and the many movements and sub-movements attending them. And of course, he is not bounded by any national borders. This is history with a capital H. That means that he has relatively little space (4-6 pp., usually at the outside) for each major figure. Thus, the book is a sweeping survey, an excellent introduction to the subject. Theory is kept to a minimum. He focuses on two aspects of Modernism--its penchant for aesthetic heresy and its stress of subjectivism.
The book is also scrupulously fair, recognizing silliness and extremism where they are found and recognizing the important realities that work designed to shock the middle class cannot exist without a middle class prepared to consume it and a society sufficiently free and stable to protect the shockers and provide them a safe place in which to work.
Personally, I would like to have seen a little more discussion of individuals who distinguished themselves but who did not subscribe to the Modernist agenda, writers such as Graham Greene or George Orwell and any number of individuals who produced magnificent work within the constraints of traditional forms. This is a book about Modernism, of course, but that could be contextualized with sharper contrasts. Gay is a believer, though a balanced one. Still, he sees grandeur in the international style of architecture and tends to overlook the ugliness of fifties' boxes with smudged glass and drip stains from flat roofs. I did not expect him to take Tom Wolfe's stance on the Bauhaus or on abstract expressionism, but Wolfe's (much-maligned) stance is shared by many. The book concludes with a survey of contemporary Modernism, with Gehry's Bilbao Guggenheim and Marquez's fiction. Gay sees the world of fiction as relatively flat, though there are many skilled practitioners. It is only flat, in my opinion, if you confine yourself to Modernist writing. Pynchon, e.g., does not fit his template and is thus not considered, though he is a towering figure. This is a small quibble in light of the book's accomplishments, however. I highly recommend it as an introduction to the subject and as an instructive, entertaining, well-written book.