Based on an extensive and successful hunt for previously unknown manuscripts containing the Jaiminiya-Upaniad-Brahmaa, the late Professor Masato Fujii offers a critical edition of this text which provides many significant improvements to the two principal previous editions. This text is the earliest Upaniad (datable to c. 500 BCE), which in a unique way forms a transition from the Brahmaas to the Upaniads. It is also an important text because of its Samavedic affinity, known for its arcane topics.The central theme is the "bodiless immortal gayatra saman ", developed by sayayani, the original eponym of the Jaiminiya school of Samaveda.