sovereign borders either presented a major barrier for Kelsen in the application of principles in international law, or represented areas where the mitigation of sovereignty could greatly facilitate the progress and effectiveness of international law in geopolitics. Law–state identity theory The understanding of Kelsen's highly functional reading of the identity of law and state continues to represent one of the most challenging barriers to students and researchers of law approaching Kelsen's writings for the first time. After Kelsen completed his doctoral dissertation on the political philosophy of Dante, he turned to the study of Jellinek's dualist theory of law and state in Heidelberg in the years leading to 1910. Kelsen found that although he had a high respect for Jellinek as a leading scholar of his day, that Jellinek endorsement of a dualist theory of law and state was an impediment to the further development of a legal science which would be supportive of the development of responsible law throughout the twentieth century in addressing the requirements of the new century for the regulation of its society and of its culture. Kelsen's highly functional reading of the state was the most compatible manner he could locate for allowing for the development of positive law in a manner compatible with the demands of twentieth century geopolitics. State–society distinctions and delineations After accepting the need for endorsing an explicit reading of the identity of law and state, Kelsen remained equally sensitive to recognizing the need for society to nonetheless express tolerance and even encourage the discussion and debate of philosophy, sociology, theology, metaphysics, sociology, politics, and religion. Culture and society were to be regulated by the state according to legislative and constitutional norms. Kelsen recognized the province of society in an extensive sense which would allow for the discussion of religion, natural law, metaphysics, the arts, etc., for the development of culture in its many and varied attributes. Very significantly, Kelsen came to the strong inclination in his writings that the discussion of justice, as one example, was appropriate to the domain of society and culture, though its dissemination within the law was highly narrow and dubious. A twentieth century version of modern law, for Kelsen, would need to very carefully and appropriately delineate the responsible discussion of philosophical justice if the science of law was to be allowed to progress in an effective manner responding to the geopolitical and domestic needs