This article is an introduction to the philosophy of mind that developed within the syncretistic rDzogs chen (Great Perfection) tradition of Tibetan Buddhism between the 8th and 14th centuries CE. Despite the growing interest in this tradition in recent decades, there has so far been no systematic appraisal of its views on mind that traces their evolution and complex relationships with antecedent Buddhist philosophies of mind. These views merit attention not only because of their intrinsic interest and relevance to contemporary consciousness studies but also because they provide an essential key to understanding the tradition’s leading ideas and practices. From a traditional standpoint, discerning the nature and structure of human consciousness in accordance with the crucial distinction between dualistic mind (sems) and primordial knowing (ye shes) is deemed indispensable to understanding rDzogs chen view and meditation. To this end, the present article focuses on how this distinction allowed rDzogs chen adepts to precisely describe, on the basis of careful first-personal observation, what occurs when a human being becomes a buddha, and to articulate a disclosive model of goal-realization commensurate with their findings. It traces the development of the distinction within its historical and doctrinal contexts and then examines its subsequent clarifications and refinements as a soteriological model. It finally summarizes the tradition’s distinctive (re)intepretations of ‘mind’ and ‘primordial knowing’, and concludes with a brief assessment of the contemporary relevance of the distinction.