This book is the Buddhist manual of psychological ethics, or Buddhist psychology, of the 4th century, B.C., being a translation, now made for the first time, from the original Pali of the First Book in the Abhidhamma-Pitaka, entitled Dhamma-Sangani (compendium of states or phenomena). It is an important text of the Theravadin School of Buddhism and deals with the enumeration of psychic and mental properties.