A staunch neoclassical economist, Rosen drew inspiration from Adam Smith's Wealth of Nations, particularly his theory of compensating wage differentials, which Rosen felt was central to all economic problems involving product differentiation and spatial considerations. The main theme of his collection is how markets handle diversity, including the determination of value in the presence of diversity, the allocation of idiosyncratic buyers to specialized sellers, and the effects of heterogeneity and sorting on inequality.