This book investigates the concept of the five “categories” (vastu) in the Buddhist Yogacara tradition. The five vastus may be understood as an attempt at categorizing all aspects of existence and as such they may probably be regarded as an alternative concept to the theory of the three “natures” (svabhava). The main focus of this book is the description of the five vastus in the Yogacarabhumi. The presentation of the five categories in this early Yogacara work provides an insight into early Yogacara thought which does not yet take into account the theory of cognition-only (vijnaptimatrata).