A staunch neoclassical economist, Sherwin 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 specialised sellers, and the effects of heterogeneity and sorting on inequality. Rosen felt that good economics required combining simple but powerful concepts such as optimising and equilibrium with careful empirical analysis. It was important for the relatively simple rules of behaviour implied by rationality to have useful, empirically descriptive content and predictive power. If they did, it was often possible to infer underlying structure (tastes and technology, for example) from actual behaviour. Using this approach, Rosen was able to develop powerful insights into such phenomena as the enormous salaries paid to sports and entertainment stars and top business executives. He also explored with fruitful results the premium paid to workers in risky jobs, learning and experience in the labour market, and other labour market phenomena.