Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Udayanacarya was a Hindu philosopher of the 10th century. He took some of the ideas of the Nyaya school and some ideas of the Vaisheshika school to formulate his own arguments, which became the root of the Navya-Ny ya school of the 13th century, established by Gangesha Upadhyaya. Hindu philosophy is divided into six stika ("orthodox") schools of thought, or darshanas (literally, "views"), which accept the Vedas as supreme revealed scriptures. The other three n stika ("heterodox") schools, which do not accept the Vedas as supreme do not form part of Hindu philosophy.