Principles of Typology is an attempt to rigorously outline all existing and possible typological systems. Even though it focuses only on one particular system, namely, the Jungian typology, it has established the foundation and the methodology that underlies all systematic thought with regard to the subject. This book starts with an outline of the axioms of typology, upon which clear and thorough definitions of functions, attitudes as well as their relations with each other has been established. The chief purpose of this volume is to clearly outline the essence of typology and provide a method for further acquisition of insight with regard to this subject. Therefore, a distinction is drawn between pure and applied typology, the type itself and personalities that inhere within the type, as well as light is shed on the proper association of those concepts. The primary purpose of the outline of such fundamental notions to the subject is to allow for the reader to be clearly aware of what we already know of Jungian typology and the core of all typological systems as well as how we can acquire further reliable knowledge. Because the method with regard to both procedures is clear and rigorous, it is likely to be reliable. This volume includes the following, two essays exploring and a thorough analysis of each type. The two essays are concerned with the aforementioned issues as well as include a critique of well known works on typology. The methodology that has been established in those essays has been utilized in the body of this work, namely, the 16 profiles where our current knowledge and possible knowledge with regard to each type has been subjected to the exactest and most thorough scrutiny possible.