The Nyāya Sūtras is a Hindu text, notable for focusing on knowledge and logic, and making no mention of Vedic rituals. The first book is structured as a general introduction and table of contents of sixteen categories of knowledge. Book two is about "pramana" (epistemology), book three is about "prameya" or the objects of knowledge, and the text discusses the nature of knowledge in remaining books. It set the foundation for Nyaya tradition of the empirical theory of validity and truth, opposing uncritical appeals to intuition or scriptural authority.