This comprehensive explanation, based on Buddha's teachings and the experiences of accomplished meditators, offers a deep insight into the nature and functions of the mind. The first part describes different types of mind in detail, revealing the depth and profundity of Buddhist understanding of human psychology, and how this can be used to improve our lives. The second part is a practical guide to devbeloping and maintaining a light, positive mind--showing how to recognize and abandon states of mind that harm us, and to replace them with peaceful and beneficial ones. The inspiring discovery we make from this is that we can attain a lasting state of joy, independent of external conditions.