The concept of civilization is highly contested, more so than most other basic concepts of the social sciences, and there is an enduring tension between its singular and plural meanings. The former tends to refer to a uniform and universal process, the latter to different cultural worlds. Both these interpretations were developed in classical sociology, and that legacy remains important for contemporary debates. More recent revivals of civilizational approaches draw on the works of Norbert Elias and Shmuel N. Eisenstadt, whose writings have highlighted the contrast between civilization in the singular and civilizations in the plural, but also opened up new perspectives of synthesis.