The volume presents a panorama of the theories of language, covering both ancient and modern theories. It deals with the origin and development of ancient theories of language with their clear and unambiguous definitions, rules and norms that offer impeccable solutions to all problems at syntactic and semantic levels. With systematic and logical explanations of language theories, the work examines ancient grammar including connection of vyakaranam with philosophy and sphota. It also takes up the origin and development of Western linguistic theories emphasising on the inability of modern linguistic science to agree on basic definitions, as of the meaning of a word, and concepts of discourse, text, macro sentence, with there being an attempt to constantly revise theories. It analyses the chief concepts studied by ancient Indian and other linguists pertaining to discourse, particularly the importance of inference in the Nyaya system of Indian philosophy and the Nyaya logical discourse. The volume will provide students and scholars of philosophy a fundamental work on linguistic theories.