Buddhist philosophy is concerned with defining and overcoming the limitations and errors of perception. To do this is essential to Buddhism's purpose of establishing a method for attaining liberation. Conceptual thought in this view can lead to a liberating understanding, a transformative religious experience. The author discusses the workings of both direct and conceptual cognition, drawing on a variety of Tibetan and Indian texts. The Gelukba interpretation of Dignaga and Dharmakirti is greatly at variance with virtually all other scholarship concerning these seminal Buddhist logicians.