The labor theory of value in classical political economy, particularly as developed in Marx's Capital, has been the source of a number of interpretations and controversies. The purpose of this paper is to make an analytical distinction between two types of labor theories of value that can illuminate the role of the less well known of the two different theories in understanding the dynamics of capital accumulation and of systemic changes. This qualitative theory of value can be used to explore the significance of value form in both capitalism and the concept and practices of socialism.It can also offer a new way of defending the right to revolt on the part of those who are exploited under both capitalism and socialism.