This book is about the power of the Word conceived as the main and most effective aspect of divine energy. It is the only systematic study in English of notions concerning the Word (Vac) as these are expounded in the shaiva tantras of Kashmir and in related texts. Padoux first describes the Vedic origins of these notions, then their development in texts of different tantric traditions. He shows how different levels of the Word abide in humans, how these levels are linked to the kun, and how they develop into articulate speech and discursive thought. He also describes how the universe is created out of the letters of the alphabet. The last two chapters explain the powers of mantras as sacred ritual utterances. These powers are described as magical as well as religious, because they can achieve supernatural results as well as lead to salvation. Their uses are linked to yogic mental and bodily practices.