a path to Self-knowledge, and this path it calls Yoga. Realize you are perfect now and here - Sixth Valli The Katha Upanishad concludes its philosophical presentation in verses 14-15 of the sixth Valli. The state of perfection, according to the last section of the Upanishad, explains Paul Deussen, consists "not in the attainment of a future or yonder world, but it is already just now and here for one who is Self-realized, who knows his Self as Brahman (Cosmic Self)". This teaching is also presented in the other ancient scriptures of Hinduism, such as Brihadaranyaka Upanishad's Chapter 4.4.6. The verse 15 of the sixth Valli declares that the Upanishad concludes its teaching therein. Yet, the Valli contains three additional verses in modern era manuscripts. Scholars suggest that these remaining verses 2.6.16 – 2.6.18 are possibly modern additions as appendix and have been interpolated. This is due to the declaration of Upanishad's end in verse 15, and the additional three verses that are structured in prose-like manner, rather than the poetic, metric-perfection that Katha Upanishad is largely written in. Reception Charles Johnston has called Katha Upanishad as one of the highest spiritual texts, with layers of metaphors embedded therein. To Johnston, the three nights and three boons in the first Valli of Katha Upanishad, for example, are among the text's many layers, with the three connoting the past, the present and the future. The Irish poet William Butler Yeats dedicated several essays and sonnets to themes in Katha Upanishad and related ancient Upanishads of India. George William Russell similarly esteemed the Katha and other Upanishads. The American poet Ralph Waldo Emerson held Katha Upanishad highly, and wrote several poems and essays paralleling the themes in it. The various themes contained in Katha Upanishad have been subject of many scholarly works. For example, Elizabeth Schiltz has compared "the parable of the chariot" in Katha Upanishad and Platonic dialogue "Phaedrus", noting the "remarkable similarities give rise to a great many tantalizing historical and literary questions", and adding the comment, "each provides an image of the self as the chariot, they each offer a complex moral psychology, and point toward an effective justification of the best life". Radhakrishnan notes that Katha Upanishad's discussion of "good versus pleasant" is evidence of ethical theories and philosophical longings of ancient human beings in India by 1st millennium BCE, much like those in Greek city states in