Kausheethaki Upanishad

The Kaushitaki Upanishad is an ancient Sanskrit text contained inside the Rigveda. It is associated with the Kaushitaki shakha, but a Sāmānya Upanishad, meaning that it is "common" to all schools of Vedanta. It is based on 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.