Twenty years ago Mr. Cairns set himself the task of looking at law from three points of view, that of the social sciences, that of logic and the empirical sciences, and that of philosophy. Law and the Social Sciences was published in 1935, the Theory of Legal Science in 1941. The volume under review completes the trilogy. The object of all these volumes is the same—‘To construct the foundation of a theory of law which is the necessary antecedeat of a possible jurisprudence’. All those who have come under the spell of Mr. Cairns' stimulating thought will look forward with the greatest interest to the application and expansion of his conclusions which is now promised us in a projected final work, The Elements of Legal Theory.