Description from Max Muller's version introduction.
"THE Katha-upanishad is probably more widely known than any other
Upanishad. It formed part of the Persian translation, was rendered
into English by Râmmohun Roy, and has since been frequently quoted by
English, French, and German writers as one of the most perfect
specimens of the mystic philosophy and poetry of the ancient Hindus.
It was in the year 1845 that I first copied at Berlin the text of this
Upanishad, the commentary of Samskara (MS. 127 Chambers 1), and the
gloss of Gopâlayogin (MS. 224 Chambers). The text and commentary of
Samskara and the gloss of Ânandagiri have since been edited by Dr.
Roer in the Bibliotheca Indica, with translation and notes. There are
other translations, more or less perfect, by Râmmohun Roy,
Windischmann, Poley, Weber, Muir, Regnaud, Gough, and others. But
there still remained many difficult and obscure portions, and I hope
that in some at least of the passages where I differ from my
predecessors, not excepting Samskara, I may have succeeded in
rendering the original meaning of the author more intelligible than it
has hitherto been.
The text of the Katha-upanishad is in some MSS. ascribed to the
Yagur-veda. In the Chambers MS. of the commentary also it is said to
belong to that Veda 2, and in the Muktikopanishad it stands first
among the Upanishads of the Black Yagur-veda. According to Colebrooke
(Miscellaneous Essays, 1, 96, note) it is referred to the Sâmaveda
also. Generally, however, it is counted as one of the Âtharvana