Although Tantra is very well-known, few understand its true significance. Some reject Buddha's tantric teachings, while others misuse them for worldly purposes. True Tantra is also known as "Secret Mantra" or "Vajrayana" and is a special method taught by Buddha to purify our world, our self, our pleasures, and our actions. If we practically implement this method and follow the guidance of a qualified spiritual master of Tantra, we will quickly attain enlightenment. This authoritative book by the Venerable Geshe Kelsang Gyatso Rinpoche provides a detailed and comprehensive explanation of the essential practices of the four classes of Tantra as taught by Buddha. He draws from his own experience in long-term tantric retreats and shows the people of the modern world how to do so.