This book offers a deep insight into the nature and functions of the human 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 developing and maintaining a light, positive mind -- showing how to recognise and abandon states of mind that harm us and replace them with peaceful and beneficial ones. The inspiring discovery we make is that we can attain a lasting state of joy, independent of external conditions.