The literary genre of science fiction is diverse, and its exact definition remains a contested question among both scholars and devotees. This lack of consensus is reflected in debates about the genre's history, particularly over determining its exact origins. There are two broad camps of thought, one that identifies the genre's roots in early fantastical works such as the Sumerian Epic of Gilgamesh (earliest Sumerian text versions c. 2150-2000 BCE). A second approach argues that science fiction only became possible sometime between the 17th and early 19th centuries, following the scientific revolution and major discoveries in astronomy, physics, and mathematics.