Although he gushes over the eleven choreographers dubbed ""prime movers,"" Mazo never tells you exactly what they did. His few descriptions of movement, even of recent performances, give no idea of how the dancers danced. For the most part Mazo tediously catalogues already published facts and tidbits of gossip in a series of personality profiles of Isadora Duncan, Ruth St. Denis, Doris Humphrey, Martha Graham, et al. A flimsy web of cultural history breaks the routine with little benefit. Mazo's observations are banal, and sometimes highly questionable. He spends much time, for instance, comparing Martha Graham to Shakespeare, and places her higher on the Parnassus of art than Humphrey on the grounds that she put more emotion into her work. In The Borzoi Book of Modern Dance Margaret Lloyd deals more vividly with the major dancers before 1945, without such critical pretensions. The fourth of Mazo's book devoted to figures after 1945, such as Merce Cunningham and Twyla Tharp, offers less information on each than on their predecessors, along with some cranky, ill-informed opinions. A good review of these major figures still remains to be written.