Each mental phenomenon has a "g-aspect" (e.g. pleasure) and an "s-aspect" (e.g. the taste of chocolate). This book is about g-aspects, the basic categories of which are derived from two principles, viz. the tripartite doctrine, and the distinction between "bottom-up" and "top-down". By combining these principles we get 27 basic categories of g-aspects, categories that seem to be in reasonably good accordance with the mental concepts of ordinary language (for example: eagerness, fear, initiative and rule-foliowing). The central concern of the present work is the definition and elucidation of the above-mentioned basic categories and the principles from which they are derived.