The present work comprises a detailed study of specific terms of discourse in the pre-twelfth century sources of esoteric "Tantric" Shaivism, both scriptural and exegetical, some of which are still unpublished and others of which are published only in the original Sanskrit. As a dissertation in South Asian Studies using the philological method, the primary purpose of the study is to ascertain the range of meanings of certain technical terms of great importance to the theology and practice of the Shaiva religion, namely avesa, samavesa, and saktipata. The work focuses on both the independent meaning and the intersection of these key terms, incorporating also the terms diksa and vedha in the latter endeavor. The intersection of these terms constitutes a complex set of relationships, a nexus of ideas that lie at the very heart of the Shaiva tradition and which, due to the latter's widespread influence, came to be important in Tantric Buddhism and later forms of Hinduism as well. This thesis contends that samavesa--meaning the fusion or commingling of one's self with the energy of one's deity and/or the consciousness of one's guru--is the key term that distinguishes Tantric Shaivism from mainstream (esp. Vaidika) Indian religion. This constitutes a reinterpretation and overcoding of the earlier meaning of avesa, i.e. self-induced controlled possession by a deity.

Samavesa is important to all forms of Shaivism, whether dualistic and ritualized (the Siddhanta) or nondual subitist charismatic forms (the Kaula). This thesis further contends that a philological study of samavesa and related terms like saktipata demonstrates that religious experience (or evidence thereof) was considered central and indispensable to initiatory Shaivism throughout the medieval period. Saktipata was requisite to receive the basic level of initiation, and in the Kaula branch of the tradition, samavesa denoted forms of religious experience that were necessary for aspirants to demonstrate in order to receive higher-level initiations. The former term is still commonly used in many Hindu communities today to designate a "spiritual awakening" or initiatory experience that is transmitted by a qualified guru.

Part One of this work is a comprehensive overview of the nature and structure of the Shaiva religion, providing important context to what follows. Part Two studies the key terms of (sam)avesa, saktipata, etc. in a) early Sanskrit literature generally, b) Shaiva scriptures, and c) the abundant exegetical literature based on those scriptures.