In quest of identity and destiny man discovered philosophy and religion. In search of realization of philosophical truth and religious summum bunum of life Lord Ýiva expounded scientific and mystic tradition known as Tantra. Tantra forms the esoteric basis of all religion and provides sound philosophical foundation of spirituality. This book presents an indepth analysis and reflection of the root concepts of Tantra such as KuÄÎalin¶, Mantra and Yantra. Tantra provides an esoteric and physiological significance of PaÛcamakŒra SŒdhanŒ. Tantra believes that poison that kills a man when scientifically cultured by physician it becomes the elixir of life. Sex when sublimated, it opens the door for salvation. Tantra is a happy and harmonious blending of enjoyment (Bhoga) and salvation (Yoga). It is neither a dogma nor lifeless rituals. It is an intuitional science. The Canonical literature of Tantra is written in Twilight language (SandhyŒ BhŒ¦Œ). Its apparent meaning is quite different from the real meaning. Only those who get initiated by a proper Guru in Tantra SŒdhanŒ understands the mystic significance of different symbols and esoteric practices. This book provides a deeper insight into the scientific and mystic significance of KuÄÎalin¶, Mantra and Yantra which are the main constituents of Tantra. This book presents a scholarly analysis and evaluation of Tantra and explains both its mystic and scientific basis.