Kundalini Yoga as taught by Yogi Bhajan® is considered the most comprehensive of yoga traditions, combining meditation, mantra, physical exercises and breathing techniques; it is a Raj Yog, encompassing the eight limbs of yoga into a singular practice of excellence and ecstasy. "Kundalini" literally means "the curl of the lock of hair of the beloved." This poetic metaphor alludes to the flow of energy and consciousness that exists within each of us, and enables us to merge with – or "yoke" – the universal Self. Fusing individual and universal consciousness creates a divine union, called "yoga." The Upanishads, dating back to the fifth century B.C., describe the kundalini, although the oral tradition reaches back even further into history. For thousands of years, this sacred science and technology was veiled in secrecy, passed along verbally from master to chosen disciple.