This nimble and witty book by one of the most important scholars of modern art is not merely the sum of two monographs on these giants of the 20th century. To the now-standard operating procedure of relativism and contextualization, Bois adds a twist. He proposes the relationship between the artists as a fitful but sustaining dialogue, rejecting as inadequate to the critical task the idea that Matisse and Picasso simply influenced one another. Drawing on diverse theoretical models in the writing of Mikhail Bakhtin, Hubert Damisch, Rene Girard and Harold Bloom, the author argues instead that for a period of over 25 years, from the late 1920s until after Matisse's death in 1954, each artist deliberately addressed his work in specific ways to the other. The theory is necessary because actual contact between the two was sporadic. This is what makes Bois's thesis about their need for one another so intriguing. What prompted this dialogue--what made the need possible, Bois asserts--was their common cause against abstraction. Prodding, teasing, paying homage, supplicating, even misunderstanding--in these and other ways Matisse and Picasso challenged each other in their mutual effort to push the envelope of representation without letting the tangibility of the world's things slip from their grasp. When they strayed into the other's long-established artistic territories (Picasso painting odalisques; Matisse working in a Cubist idiom) they were sending signals to each other above the artistic fray, in a kind of Olympian fraternal sympathy. This sealing off of Matisse's and Picasso's artistic communication from the rest of the world is the most controversial aspect of the book, as it was of the beautiful exhibition it accompanied at the Kimbell Art Museum in Fort Worth, Texas. Bois frankly calls his effort an "experiment" in which it is necessary to isolate variables, studying them carefully in relation to one another, with the relationship itself as the constant factor. This scientific conceit of "let's see what happens" is undermined by the humanistic drive to demonstrate a thesis. And we should be thankful for that. Like the best publications arising from exhibitions, this book will have independent, lasting value, but it will also be more provocative than most.