This book sets out to explore the doctrinal dimension of classical Hinduism (eighth century BCE to circa 1000 CE.), and is organized in terms of its key concepts: brahman, karma, karma-yoga, etc. which are discussed in their logical connection as well as in the context of a period of Hinduism which is chronologically connected with those that precede and succeed it. In textual terms, this covers the period from the Upanishads down to the late Purānas, and all that comes between them: the Smrtis (law books), the Itihāsas (epics), the Purānas (ancient lore), the Āgamas (liturgical manuals) and Darśanas (philosophical literature), etc. The purpose of the book is to synchronically and systematically present the governing concepts of classical Hinduism and their operation during the delimited period of classical Hinduism. Three features of the book to enable readers to use it to full advantage: (1) the first chapter constitutes the text of an oral presentation made at the Smithsonian Institution, designed to present classical Hindu thought in a concise and accessible manner. It forms a useful introduction to the conceptual framework of Hinduism, as the key ideas have deliberately been presented in a simple and direct manner. Their complexities and nuances are uncovered under the specific chapters that follow. (2) The rest of the book may be viewed as a magnification of the first chapter. (3) Among the essentials of classical Hindu thought, special and detailed consideration has been accorded to the concept of varna.