The Katha Upanishad, also titled "Death as Teacher", is one of the mukhya ("primary") Upanishads commented upon by Shankara. It is associated with the Cāraka-Kaṭha school of the Black Yajurveda, and is grouped with the Sutra period of Vedic Sanskrit. It is a middle Upanishad. It contains passages that suggest contact with Buddhist ideas, so was likely composed after the fifth century BCE. It figures as number 3 in the Muktika canon of 108 Upanishads. It consists of two chapters (adhyāyas), each divided into three sections (vallis) that contain between 15 and 29 verses (ślokas) apiece. The Katha has some passages in common with the Gita. According to modern scholars, it propounds a dualistic philosophy.