central character in the Katha Upanishad legend, similarly, has closely related words with roots and meanings relevant to the text. Paul Deussen suggests Na kṣiti and Na aksiyete, which are word plays of and pronounced similar to Nachiketa, means "non-decay, or what does not decay", a meaning that is relevant to second boon portion of the Nachiketa story. Similarly, Na jiti is another word play and means "that which cannot be vanquished", which is contextually relevant to the Nachiketa's third boon. Both Whitney and Deussen independently suggest yet another variation to Nachiketa, with etymological roots that is relevant to Katha Upanishad: the word Na-ciketa also means "I do not know, or he does not know". Some of these Sanskrit word plays are incorporated within the Upanishad's text. Like Taittiriya Upanishad of Yajurveda, each section of the Katha Upanishad is called a Valli (वल्ली), which literally means a medicinal vine-like climbing plant that grows independently yet is attached to a main tree. Paul Deussen states that this symbolic terminology is apt and likely reflects the root and nature of the Upanishads in Black Yajur veda, which too is largely independent of the liturgical Yajur Veda, and is attached to the main text. Chronology The chronology of Katha Upanishad is unclear and contested by scholars. All opinions rest on scanty evidence, an analysis of archaism, style and repetitions across texts, driven by assumptions about likely evolution of ideas, and on presumptions about which philosophy might have influenced which other Indian philosophies. Richard King and A.L. Basham date the Katha Upanishad's composition roughly to the 5th century BCE, chronologically placing it after the first Buddhist Pali canons. Olivelle assigns the Katha Upanishad to the verse Upanishads, together with the Kena, Isa, Svetasvatara, and Mundaka, dating it to the first centuries BCE. Paul Deussen too considers Katha Upanishad to be a post-prose, yet earlier stage Upanishad composed about the time Kena and Isha Upanishads were, because of the poetic, mathematical metric structure of its hymns. Stephen Phillips notes the disagreement between modern scholars. Phillips places the Katha Upanishad chronologically after Brihadaranyaka, Chandogya, Isha, Taittiriya, Aitareya and Kena, but before Mundaka, Prasna, Mandukya, Svetasvatara and Maitri Upanishads, as well as before the earliest Buddhist Pali and Jaina canons. Winternitz considers the Kathaka Upanishad as pre-Buddhist, pre-Jaina literature. Structure The Katha Upanishad has two chapters, each with three sections (valli), thus a total of six sections.