The book is based primarily on the source material available in the Pali Canon, studied historically and philosophically in the light of the contemporary, earlier and later literary evidence related to the subject. The antiquity and authenticity of material is vouchsafed by literary, linguistic, ideological, sociological and historical evidence existing in the Pali Cannon itself. The book traces the origin of the theory of knowledge and its development in early Buddhism- the Hinayana Buddhism of Pali Cannon.