Kenopanishad is found in the Talavakara Brahmana of Jaimini sakha of Samaveda. Also called Talavakara Upanishad, it has four chapters and 35 mantras and gets its name by its very first word ‘Kena’ which means, ‘By What’.
This Upanishad has a beautiful exposition on the self, which is the eye of the eye, ear of ear, mind of the mind etc. and specially mentions the basic disciplines needed to attain knowledge of Brahman.
These talks deal with the 1st of the four chapters.