Authority and eternal truths play an important role in Hinduism. Religious traditions and truths are believed to be contained in its sacred texts, which are accessed and taught by sages, gurus, saints or avatars. But there is also a strong tradition of the questioning of authority, internal debate and challenging of religious texts in Hinduism. The Hindus believe that this deepens the understanding of the eternal truths and further develops the tradition. Authority was mediated through [...] an intellectual culture that tended to develop ideas collaboratively, and according to the shared logic of natural reason. Narratives in the Upanishads present characters questioning persons of authority. The Kena Upanishad repeatedly asks kena, 'by what' power something is the case. The Katha Upanishad and Bhagavad Gita present narratives where the student criticizes the teacher's inferior answers. In the Shiva Purana, Shiva questions Vishnu and Brahma. Doubt plays a repeated role in the Mahabharata. Jayadeva's Gita Govinda presents criticism via the character of Radha.