The two types of meditation that form the core of Buddhist spiritual practice are: tranquillity (samatha) meditation aims at stilling the mind, while insight (vipasyana) meditation produces clear vision or insight into the nature of all phenomena. With masterful scholarship, Rinpoche explains this unified system of meditationandmdash;what to do, what to avoid, and the stages of deepening meditationandmdash;so the practitioner can gauge progress. His teaching is a commentary on the eighth chapter of the Treasury of Knowledge by Jamgon Kongtrul.