"No condition is permanent," a popular West African slogan, expresses Sara S. Berry's theme: the obstacles to African agrarian development never stay the same.  Her book explores the complex way African economy and society are tied to issues of land and labor, offering a comparative study of agrarian change in four rural economies in sub-Saharan Africa, including two that experienced long periods of expanding peasant production for export (southern Ghana and southwestern Nigeria), a settler economy (central Kenya), and a rural labor reserve (northeastern Zambia).      The resources available to African farmers have changed dramatically over the course of the twentieth century.  Berry asserts that the ways resources are acquired and used are shaped not only by  the incorporation of a rural area into colonial (later national) and global political economies, but also by conflicts over culture, power, and property within and beyond rural communities.  By tracing the various debates over rights to resources and their effects on agricultural production and farmers' uses of income, Berry presents agrarian change as a series of on-going processes rather than a set of discrete "successes" and "failures."      No Condition Is Permanent enriches the discussion of agrarian development by showing how  multidisciplinary studies of local agrarian history can constructively contribute to development policy.  The book is a contribution both to African agrarian history and to debates over the role of agriculture in Africa's recent economic crises.