The Sanskrit Tradition of Grammar and Linguistics, along with its history, is presented in view of texts and trends, where structure and content of the Ashtadhyayi find their focus on rule formulation, interpretation, and interaction. My proposal of derivation is made in view of what Panini does (acarya-pravritti) with rules of the Ashtadhyayi, and what statements (vyakhyana) were made on a given topic by Patanjali. My presentation is all tied in with the interpretive conventions # (2) yathoddeshah samjna-paribhasham, and # (3) karyakalam samjna-paribhasham (PS) of Nagesha. It yields two kinds of ekavakyata considerations where one facilitates interpretation of a rule within adhikakars, and the other facilitates ekavakyata across domains, with no anuvritti consideration. Finally the derivational history yields a string of definitions which not only offer direction to individual derivations but also projects what rules will apply when and on what kind of string. Why does Panini repeat the use of definition terms in the Ashtadhyayi, so that they can clearly chart the path of derivation, and facilitate reconstruction of history of derivation? This all is new, and is in consonance with the tradition. The last section of this book presents a comprehensive view of modern studies on Panini to modern times.