Until the discovery of the Library of Nag Hammadi in 1945, "Against Heresies" was the best-surviving description of Gnosticism. Some religious scholars have argued the findings at Nag Hammadi have shown Irenaeus' description of Gnosticism to be inaccurate and polemic in nature. However, the general consensus among modern scholars is that Irenaeus was fairly accurate in his transmission of Gnostic beliefs, and that the Nag Hammadi texts have raised no substantial challenges to the overall accuracy of Irenaeus' information. Religious historian Elaine Pagels criticizes Irenaeus for describing Gnostic groups as sexual libertines, for example, when some of their own writings advocated chastity more strongly than did orthodox texts. However, the Nag Hammadi texts do not present a single, coherent picture of any unified Gnostic system of belief, but rather divergent beliefs of multiple Gnostic sects. Some of these sects were indeed libertine because they considered bodily existence meaningless; others praised chastity, and strongly prohibited any sexual activity, even within marriage.